The Postnatal Leptin Surge Supports Immune Cell Function in Rats.

BACKGROUND: Leptin plays an important role in the regulation of the immune response. There is a physiological surge of leptin in rodents during the neonatal period, which has mainly been studied in the context of brain development. However, little is known about the effects of this neonatal leptin surge on immunity. Therefore, we investigated whether blocking this leptin surge could affect several immune functions. METHODS: Male and female rats were injected subcutaneously with 5 mg/Kg/day of rat pegylated super leptin antagonist during the neonatal period (PND5-9). On the peripubertal period, relevant functions as well as cytokine release by spleen leukocytes were studied in these animals. RESULTS: The results showed that the animals significantly display an impaired anti-tumor NK activity and chemotactic and proliferation capacity of lymphocytes in response to mitogens. In addition, several cytokine concentrations, released under mitogen-stimulated conditions, were also altered. CONCLUSION: In conclusion, the neonatal leptin surge seems to be involved in the establishment of an adequate immune response and cytokine profile, which are crucial for the maintenance of a healthy life.

Is Carriage of Leptospira interrogans by Rats Influenced by the Urban Environment or Population Density?

Leptospira interrogans is one of the most important zoonotic pathogens globally. In urban settings, Norway rats (Rattus norvegicus) are important reservoirs of L. interrogans, but it is unclear how this bacterium is transmitted among rats. Both environmental features and rat population density may determine the prevalence of this pathogen in rat populations as well as the spillover risk to people. While these factors could play an important role in transmission between rats, it is unknown whether such factors influence prevalence among rats at a fine scale. Our objective was to determine if carriage of L. interrogans by rats could be explained by variation in the environment or in rat population density. Rats were live-trapped in a single neighborhood of Vancouver, Canada during two study periods (2011-12; 2016-17) and were tested for L. interrogans. The physical environment of each city block was recorded using a comprehensive, in-person environmental survey. Using generalized linear mixed modelling, we found no evidence of an association between carriage of L. interrogans and environmental features or rat population density, suggesting that these were not the primary drivers of its distribution among rats within this neighborhood. Understanding factors that promote L. interrogans transmission can be used to inform management approaches to minimize public health risks.

Effects of Dietary Protein from Different Sources on Biotransformation, Antioxidation, and Inflammation in the Rat Liver.

In this work, the effects of different sources of meat protein on liver metabolic enzymes were investigated. Rats were fed for 90 days with semisynthetic diets in which casein was fully replaced by isolated soybean, fish, chicken, pork, or beef proteins. Then, liver proteomics was performed using iTRAQ and LC-ESI-MS/MS. The results indicated that intake of meat protein diets significantly reduced the protein levels of CYP450s, GSTs, UGTs, and SULTs compared to those of the casein and soybean protein diet groups. The total antioxidant capacity and lipid peroxidation values did not differ between four meat protein diet groups and the casein diet group. However, GSH activity in the fish, chicken, and beef protein groups was significantly higher than those of the casein and soybean protein groups. The beef protein diet significantly upregulated the expression of immune-related proteins. The Keap1-Nrf2-ARE signaling pathway was suggested to involve the diet-mediated regulation of biotransformation, inflammation, and redox status.

Selected Molecular Mechanisms Involved in the Parasite⁻Host System Hymenolepis diminuta⁻Rattus norvegicus.

The rat tapeworm Hymenolepis diminuta is a parasite of the small intestine of rodents (mainly mice and rats), and accidentally humans. It is classified as a non-invasive tapeworm due to the lack of hooks on the tapeworm's scolex, which could cause mechanical damage to host tissues. However, many studies have shown that metabolites secreted by H. diminuta interfere with the functioning of the host's gastrointestinal tract, causing an increase in salivary secretion, suppression of gastric acid secretion, and an increase in the trypsin activity in the duodenum chyme. Our work presents the biochemical and molecular mechanisms of a parasite-host interaction, including the influence on ion transport and host intestinal microflora, morphology and biochemical parameters of blood, secretion of antioxidant enzymes, expression of Toll-like receptors, mechanisms of immune response, as well as the expression and activity of cyclooxygenases. We emphasize the interrelations between the parasite and the host at the cellular level resulting from the direct impact of the parasite as well as host defense reactions that lead to changes in the host's tissues and organs.

Collagen-induced arthritis in Dark Agouti rats as a model for study of immunological sexual dimorphisms in the human disease.

Collagen-induced arthritis (CIA) is a frequently used animal model of rheumatoid arthritis, human autoimmune disease that exhibits clear sex bias in incidence and clinical course. Female Dark Agouti rats immunized for CIA showed also greater incidence and higher arthritic score than their male counterparts. The study investigated sex differences in mechanisms controlling the primary immune responses in draining lymph nodes (dLNs), as a factor contributing to this dimorphism. The higher frequencies of CD4 + CD25 + Foxp3- cells, presumably activated effector T (Teff) cells, and IL-17+, IFN-γ + and IL-17 + IFN-γ + T cells were found in female compared with male rat dLNs. However, the frequency of CD4 + CD25 + Foxp3+ T regulatory cells (Treg) did not differ between sexes. Thus, CD4+ Teff cells/Treg ratio, and IL-17+ T cells/Treg and IFN-γ + T cells/Treg ratios were higher in female than in male rats, and among them was found lower frequency of PD-1+ cells. This suggested less efficient control of (auto)immune Th1/Th17 cell responses in female rat dLNs. On the contrary, the frequency of IL-4+ T cells was lower in female than in male rat dLNs. Consistently, the ratio of serum levels of collagen-specific IgG2a (IFN-γ-dependent, with an important pathogenic role in CIA) and IgG1 (IL-4-dependent) was shifted towards IgG2a in female compared with male rats. As a whole, the study suggests that sexual dimorphism in the control of T cell activation/polarization could contribute to sex bias in the susceptibility to CIA. Moreover, the study advises the use of animals of both sexes in the preclinical testing of new drugs for rheumatoid arthritis.

Immune defense of wild-caught Norway rats is characterized by increased levels of basal activity but reduced capability to respond to further immune stimulation.

Studies of wild animals' immunity often use comparison with laboratory-raised individuals. Using such an approach, various data were obtained concerning wild Norway rat's immunity. Lower or higher potential of immune system cells to respond to activation stimuli were shown, because of analysis of disparate parameters and/ or small number of analyzed individuals. Inconsistent differences between laboratory and wild rats were shown too, owing to great response variability in wild rats. We hypothesized that wild rats will express more intense immune activity compared to their laboratory counterparts which live in a less demanding environment. To test this, we analyzed the circulating levels of inflammatory cytokine interleukin-6 (IL-6), a mediator which has a central role in host immune defense. In addition, we examined the activity of the central immune organ, the spleen, including cell proliferation and production of pro-inflammatory cytokines interferon-γ (IFN-γ) and interleukin-17 (IL-17), which are major effectors of cellular adaptive immune response. In order to obtain reasonable insight into the immunity of wild Norway rats, analysis was conducted on a much larger number of individuals compared to other studies. Higher levels of plasma IL-6, higher spleen mass, cellularity and basal IFN-γ production concomitantly with lower basal production of anti-inflammatory cytokine interleukin-10 (IL-10) revealed more intense immune activity in the wild compared to laboratory rats. However, lower responsiveness of their spleen cells' proinflammatory cytokine production to concanavalin A (ConA) stimulation, along with preserved capacity of IL-10 response, might be perceived as an indication of wild rats' reduced capability to cope with incoming environmental stimuli, but also as a means to limit tissue damage.

Generation of Methicillin-Resistant Staphylococcus Aureus Biofilm Infection in an Immunosuppressed Rat Model.

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen responsible for many related infections, and immunosuppressed individuals are more susceptible. Its pathogenicity is associated with its virulence factors, resistance to antibiotics, and ability to form biofilm (BF). MRSA-BF infections in immunosuppressed patients pose great difficulties to clinical treatment. MATERIAL AND METHODS The study aimed to establish a model of MRSA-BF infection in rats with cyclophosphamide (CTX)-induced immunosuppression. For this, rats were administered CTX on days 1 and 4. White blood cells (WBC) were counted, then rats were inoculated with a clinical MRSA 17546 (t037) on day 5. Rats were sacrificed on days 6-10 and tissue samples were examined by scanning electron microscopy. RESULTS Using the dose of CTX: 150 (mg/kg) + 100 (mg/kg) is better than the other 2 programs as the survival rates of the immunocompromised rats were higher than in the other 2 immunosuppressive groups. The survival rate was not different between rats in the clean environment and in the SPF environment. However, the survival rate was affected by the sample acquisitions. Importantly, WBC counts started to decline on day 4, and then started to rise on day 9. Moreover, MRSA-BFs were formed earlier in immunosuppressed rats compared to the normal rats, as shown by scanning electron microscopy. CONCLUSIONS The study successfully established an immunosuppressed rat model of MRSA-BF infection, which provides methodological and data support for establishment of such animal models and is useful reference for related research. Our results may help further investigation of MRSA-BF infection.

Comparison of Allogeneic and Syngeneic Rat Glioma Models by Using MRI and Histopathologic Evaluation.

Research in neurooncology traditionally requires appropriate in vivo animal models, on which therapeutic strategies are tested before human trials are designed and proceed. Several reproducible animal experimental models, in which human physiologic conditions can be mimicked, are available for studying glioblastoma multiforme. In an ideal rat model, the tumor is of glial origin, grows in predictable and reproducible patterns, closely resembles human gliomas histopathologically, and is weakly or nonimmunogenic. In the current study, we used MRI and histopathologic evaluation to compare the most widely used allogeneic rat glioma model, C6-Wistar, with the F98-Fischer syngeneic rat glioma model in terms of percentage tumor growth or regression and growth rate. In vivo MRI demonstrated considerable variation in tumor volume and frequency between the 2 rat models despite the same stereotactic implantation technique. Faster and more reproducible glioma growth occurred in the immunoresponsive environment of the F98-Fischer model, because the immune response is minimized toward syngeneic cells. The marked inability of the C6-Wistar allogeneic system to generate a reproducible model and the episodes of spontaneous tumor regression with this system may have been due to the increased humoral and cellular immune responses after tumor implantation.

Can serum cytokine profile discriminate irritant-induced and allergen-induced symptoms? A cross-sectional study in workers mostly exposed to laboratory animals.

BACKGROUND: In workers exposed mostly to laboratory animals (LA), symptoms may be due to irritants or allergens. Correct aetiological diagnosis is important for health surveillance. OBJECTIVES: This study aims to test whether work-related (WR) allergen-induced symptoms are associated with a cytokine profile distinct from that due to irritants. METHODS: In a cross-sectional study (n=114), WR respiratory and/or skin symptoms were assessed through a standardised clinical examination and sensitisation to rat and/or mouse allergen determined by serum immunoglobulin E. Serum cytokine concentrations were measured by multiplex assays. The predefined cytokine profiles 'sensitiser' (interleukin (IL)-4, IL-5, IL-13, eotaxin-1) and 'irritation' (IL-8, IL-17A, IL-17F, IL-22) were considered positive, when ≥3 concentrations exceeded the 95th percentile of the asymptomatic non-sensitised group. Results were examined by hierarchical clustering analyses (HCA) and multiple linear regression. Explorative analyses were carried out for nine additional cytokines. Exposure to allergens and endotoxin was assessed in a subpopulation. RESULTS: The prevalence of the profile 'irritation' was comparable in 28 symptomatic non-sensitised workers and 71 asymptomatic non-sensitised workers. HCA showed that nearly all symptomatic non-sensitised workers were gathered in two subclusters, characterised by high IL-17A levels, but different IL-8 levels. Multiple linear regression identified drug consumption and current complaints as confounders. Sensitised subjects were too few (n=14) for testing the profile 'sensitiser'. CONCLUSIONS: In this unselected population of LA workers, the profile 'irritation' did not prove to be a valuable health surveillance tool. Low power precluded assessment of the profile 'sensitiser'. The increased IL-17A concentration may originate from irritative constituents of organic dust.

Autoimmune Encephalitis in Postpartum Psychosis.

OBJECTIVE: Significant immunological alterations have been observed in women with first-onset affective psychosis during the postpartum period. Recent studies have highlighted the possibility that a subset of patients with first-onset severe psychiatric episodes might suffer from undiagnosed autoimmune encephalitis. Therefore, the authors performed a three-step immunohistochemistry-based screening for CNS autoantibodies in a large cohort of patients with postpartum psychosis and matched postpartum comparison subjects. METHOD: Ninety-six consecutive patients with postpartum psychosis and 64 healthy postpartum women were included. Screening for antibodies in patient serum was performed using immunohistochemistry. Samples showing any staining were further examined by immunocytochemistry using live hippocampal neurons and cell-based assays to test for anti-N-methyl-d-aspartate (NMDA) receptor antibodies. Cell-based assays for all other known CNS antigens were performed in those samples with immunocytochemistry labeling but negative for NMDA receptor antibodies. RESULTS: Four patients (4%) with neuropil labeling suggestive for extracellular antigen reactivity were identified. Serum samples from all four patients showed clear extracellular labeling of live hippocampal neurons. Two women had the specific staining pattern characteristic for anti-NMDA receptor antibody positivity, which was confirmed by cell-based assays. Neither patient with anti-NMDA receptor antibody positivity had evidence of an ovarian teratoma. The other two patients tested negative by cell-based assays for all known CNS antigens. None of the matched postpartum comparison subjects had confirmed neuronal surface antibodies. The two patients with anti-NMDA receptor antibodies both showed extrapyramidal symptoms following initiation of treatment with low-dose haloperidol. CONCLUSIONS: In patients with acute psychosis during the postpartum period, systematic screening for anti-NMDA receptor autoantibodies should be considered. The acute onset of severe atypical psychiatric symptoms in young female patients should raise the index of suspicion for anti-NMDA receptor encephalitis, particularly in the setting of neurological symptoms, including extrapyramidal side effects of antipsychotic treatment.

Effect of multilevel laboratory rat caging system on the well-being of the singly-housed Sprague Dawley rat.

Current regulations emphasize that good husbandry practices allow animals to engage in species appropriate postural adjustments without touching the enclosure walls. This study evaluated the well-being of rats housed in a commercially available multilevel rat caging system, with or without access to the upper level of the caging. The evaluation methodologies included assessment of behavioral observations in the home cage, physiological assessment of metabolism and immune function, and determination of the affective state using a spatial cognitive bias assay. The study determined that rats that were provided access to the full multilevel cage during testing after initial restriction to the lower level of the cage demonstrated behavioral changes consistent with a positive affective state, while those with no changes to their housing situation had no significant differences in their affective states. Rats that were consistently housed with access restricted to the lower level of the cage exhibited a tendency to increased neutrophil:lymphocyte ratios as compared with those provided with access to all levels of the multilevel cage. There were no differences in body weight demonstrated between the experimental groups. Overall use of the cage space, as documented through analysis of behavioral observations in the home cage, demonstrated no significant differences in preferred location in the cage during the light or dark cycles, though rats with access to both levels of the cage were significantly more active during the light cycle. The results of this study suggest that the use of a multilevel caging system may improve the well-being of rats used in research.

The laboratory mouse and wild immunology.

The laboratory mouse, Mus musculus domesticus, has been the workhorse of the very successful laboratory study of mammalian immunology. These studies--discovering how the mammalian immune system can work--have allowed the development of the field of wild immunology that is seeking to understand how the immune responses of wild animals contributes to animals' fitness. Remarkably, there have hardly been any studies of the immunology of wild M. musculus domesticus (or of rats, another common laboratory model), but the general finding is that these wild animals are more immunologically responsive, compared with their laboratory domesticated comparators. This difference probably reflects the comparatively greater previous exposure to antigens of these wild-caught animals. There are now excellent prospects for laboratory mouse immunology to make major advances in the field of wild immunology.

[Immunoallergic skin manifestations associated with new pets: three cases]. / Manifestations cutanées immuno-allergiques liées aux nouveaux animaux de compagnie : trois observations.

BACKGROUND: The number of household pets increased greatly during the twentieth century, with numbers of new pets (NP, i.e. any pets other than cats and dogs) rising especially sharply over the last decade. PATIENTS AND METHODS: We first of all report the case of a female patient with eczema lesions on areas skin coming into contact with a ferret, with removal of the animal resulting in wound healing, followed by two patients presenting atypical polymorphous erythema reactions induced by dermatophytes present in their pet rat. DISCUSSION: While the most common allergies are respiratory, allergic skin reactions, both immediate and delayed, may also result from contact with these new allergens. The animal itself or its environment may be the cause.

Systemic injection of low-dose lipopolysaccharide fails to break down the blood-brain barrier or activate the TLR4-MyD88 pathway in neonatal rat brain.

We aimed to investigate whether peripheral low-dose lipopolysaccharide (LPS) induces the breakdown of the blood-brain barrier (BBB) and/or the activation of toll-like receptor 4 (TLR4) in the neonatal rat brain. Neonatal rats received intraperitoneal injections of low-dose LPS (0.3 mg/kg∙bw), and the BBB compromise was detected by Evans Blue extravasation and electron microscopy. Meanwhile, TLR4, adaptin myeloid differentiation factor 88 (MyD88), nuclear transcription factor kappa-B (NF-κB) p50 and tumor necrosis factor alpha (TNFα) in the neonatal rat brain were determined by quantitative real-time polymerase chain reaction (PCR) and Western Blot. Immunohistochemistry was used to determine the distribution and activation of microglia in the brain after LPS administration. It was demonstrated that Evans Blue extravasation was not observed in the brain parenchyma, and that tight junctions of cerebral endothelial cells remained intact after systemic injections of LPS in neonatal rats. Although intracerebroventricular injections of LPS activated microglia and up-regulated the expression of TLR4, MyD88, NF-κB p50 and TNFα in the neonatal rat brain, systemic LPS did not induce these responses. These findings indicate that while the neonatal rat brain responds to the direct intra-cerebral administration of LPS through robust TLR4 activation, systemic low-dose LPS does not induce the innate immune reaction or compromise the BBB in neonatal rats.

Active immunization against GnRH reduces the synthesis of GnRH in male rats.

We sought to determine the effects of active anti-GnRH immunization on GnRH synthesis in the hypothalamus. Adult male rats (n = 36) were randomly and equally allocated into three groups: Control (no treatment), surgically castrated, or immunized against 50 µg D-Lys6-GnRH-tandem-dimer peptide conjugated to ovalbumin in Specol adjuvant at 12 week of age (with a booster 8 week later). Blood samples (for antibody titers and hormone concentrations) were collected at 2-week intervals until rats were killed (20 week). Compared with intact controls, immunocastration reduced (P < 0.05) serum concentrations of testosterone, LH, and FSH, and GnRH content in the median eminence, reduced the weight of the hypohysis (P < 0.01), and induced testicular atrophy (suppression of spermatogenesis). Furthermore, mRNA expression of GnRH in the hypothalamus, GnRH receptor, LH-ß and FSH-ß in the pituitary, LH receptor and FSH receptor in the testes, and genes in sex steroid feedback loops (androgen receptor [AR], kisspeptin encoded gene (Kiss-1), and kisspeptin receptor (GPR54) in the hypothalamus were decreased in immunocastrated rats compared with intact controls (P < 0.05). Similarly, surgical castration reduced GnRH in the median eminence as well as mRNA expression of GnRH, AR, Kiss-1, and GPR54 in the hypothalamus (P < 0.05). We concluded that anti-GnRH immunization in adult rats reduced synthesis of hypothalamic GnRH by decreasing androgen-AR-Kisspeptin-GPR54 signaling pathways, and caused dysfunction of the pituitary-testicular axis, thereby suppressing spermatogenesis, resulting in testicular atrophy.

The relationship between a specific IgE level and asthma outcomes: results from the 2005-2006 National Health and Nutrition Examination Survey.

BACKGROUND: Allergen exposure is associated with increased specific IgE (sIgE), and allergen exposure plus sensitization is predictive of asthma outcomes. However, it is not known if sIgE is predictive of asthma outcomes in the absence of exposure data. OBJECTIVE: To investigate whether IgE to indoor allergens is predictive of and has a dose-response relationship with asthma emergency department (ED) visits and wheeze. METHODS: In the 2005-2006 National Health and Nutrition Examination Survey, 351 children and 390 adults reported current asthma. Continuous sIgE to 9 indoor allergens were considered. Asthma morbidity in the past year was measured by wheezing. Health care utilization was defined as any asthma ED visits in the past year. RESULTS: Analyses were adjusted for race, age, education, poverty index ratio and (in adults) tobacco use. In children, ED visits were associated with cockroach (odds ratio [OR] 1.5 [95% CI, 1.1-2 .1), rat (OR 1.9 [95% CI, 1.2-2.8]), and Aspergillus (OR 1.6 [95% CI, 1.001-2.60]). Continuous Aspergillus (OR 1.5 [95% CI, 1.04-2.1), Alternaria (OR 1.4 [95% CI, 1.1-1.6]), and total IgE (OR 1.2 [95% CI, 1.1-1.4]) were associated with wheeze in children. Adult ED visits were associated with sIgE for dust mites (Dermatophagoides pteronyssinus OR 1.6 [95% CI, 1.3-2.1]; Dermatophagoides farinae OR 1.6 [95% CI, 1.3-1.9]), total IgE (OR 1.4 [95% CI, 1.04- 1.9]), and the sum of sIgEs (OR 1.6 [95% CI, 1.2-2.2]). CONCLUSIONS: Sensitization to particular indoor environmental allergens was found to be a risk factor for wheeze and asthma ED visits. These outcomes increased as the concentration of sIgE to these allergens increased.

Frequent detection and characterization of hepatitis E virus variants in wild rats (Rattus rattus) in Indonesia.

One hundred sixteen rats (Rattus rattus) captured in Indonesia from 2011 to 2012 were investigated for the prevalence of hepatitis E virus (HEV)-specific antibodies and HEV RNA. Using an ELISA based on HEV genotype 4 with an ad hoc cutoff value of 0.500, 18.1 % of the rats tested positive for anti-HEV IgG. By nested RT-PCR, 14.7 % of the rats had rat HEV RNA, and none were positive for HEV genotype 1-4. A high HEV prevalence among rats was associated with lower sanitary conditions in areas with a high population density. Sixteen of the 17 HEV isolates obtained from infected rats showed >93.0 % nucleotide sequence identity within the 840-nucleotide ORF1-ORF2 sequence and were most closely related to a Vietnamese strain (85.9-87.9 % identity), while the remaining isolate differed from known rat HEV strains by 18.8-23.3 % and may belong to a novel lineage of rat HEV. These results suggest a wide distribution of rat HEV with divergent genomes.

Sensitization to rodents (mouse/rat) in an urban atopic population without occupational exposure living in Naples, Italy.

BACKGROUND: Until now no data on allergic sensitization to rodents allergens in Western Europe and Italy are available. The aim of this report was to investigate clinical significance and characteristics of IgE-mediated sensitization to mouse/rat (M/Rt) allergens in atopic subjects not occupationally exposed to these animals and living in urban area of Naples. METHODS: In 1765 consecutive outpatients, we selected all subjects with an immediate skin reaction to M/WRt dander clinical history including a carefijul evaluation ofthe modality of exposure, the results of skin-prick tests (SPTs) and specific IgE antibodies were recorded. RESULTS: Among 1185 SPT-positive patients, 22 were sensitized to M/Rt dander (respectively 1.60% and 0.59%). No patient was mono-sensitized Only three of 22 patients reported indoor conditions suggesting presence of rodents allergens at home. All patients exhibited low degree of SPT positivity and low levels of circulating IgE antibodies to M/WRt. Highfrequency of concomitant allergic sensitization to pet (and other animal) dander has been found. CONCLUSIONS: Our results suggest that role of allergic sensitization to rodents is negligible in atopic subjects without occupational exposure living in urban area of Naples. However, highly atopic individuals especially those already sensitized to common pet dander should be tested by SPTs/evaluation of serum specific IgE to rodents in the case they could begin an occupational exposure to M/Rt or keeping these animals as pets.

Exposure of laboratory animal care workers to airborne mouse and rat allergens.

Urine of rats and mice is the main source of allergenic proteins that can enter the respiratory tract of laboratory animal care workers. Little is known about the levels and determinants of these exposures in the United States. We investigated the relationship between activities in animal facilities and levels of personal exposure to allergen by collecting personal breathing zone dust samples from 7 caretakers during full workdays for 1 wk. Mice and rat urinary allergens in inhalable dust were quantified via immunoassay. The activities of the sampled workers were observed, and the methods of preventing exposure to allergens were recorded. Mouse urinary allergen was detected in 20 of 39 measurements, yielding a geometric mean of 0.8 ng/m(3) with a maximum of 24 ng/m(3). Washing and cleaning cages and the number of mice handled daily were the most important determinants of personal exposure to mouse urinary allergen, as identified by using multiple linear regressions that explained 51% of total variance. Personal exposures to mouse urinary allergen were associated with day-to-day variation of tasks rather than characteristics of workers. Where potential for personal exposure is the highest, protective measures (N95 masks and cage dumping stations) appeared to be used, as is appropriate. Rat urinary allergen was detected in 4 of 39 measurements; detectable concentrations were between 0.8 and 39 ng/m(3). Only persons who handled rats were exposed to rat urinary allergen. The current findings are valuable for establishing exposure levels against which comparisons of improvement or deterioration of personal exposures can be made.

The germfree murine animal: an important animal model for research on the relationship between gut microbiota and the host.

Scientific findings in recent decades have demonstrated that the commensal intestinal microbiota has profound effects on the physiology and diseases of the host. It is estimated that the human microbiota is composed of 10(14) bacterial cells, a number 10 times greater than the total number of human cells. The variety and the complex interactions of the intestinal microbiota are associated with physiological details that remain largely unknown. Germfree hosts, especially murine (rat or mouse) animals that have been maintained free from demonstrable microbial associates such as bacteria, viruses, fungi, and parasites throughout life, have become a powerful tool for exploring the interplay between the host and microorganisms inhabiting the human intestine. This review and survey of recent findings will argue that the germfree mouse model can produce its greatest potential benefits in the study of the metabolism and immunity of the host.