Sigmodontinae
Muridae
South America
Rodent Diseases
High aerobic capacities in the skeletal muscles of pinnipeds: adaptations to diving hypoxia. (1/270)
The objective was to assess the aerobic capacity of skeletal muscles in pinnipeds. Samples of swimming and nonswimming muscles were collected from Steller sea lions (Eumetopias jubatus, n = 27), Northern fur seals (Callorhinus ursinus, n = 5), and harbor seals (Phoca vitulina, n = 37) by using a needle biopsy technique. Samples were either immediately fixed in 2% glutaraldehyde or frozen in liquid nitrogen. The volume density of mitochondria, myoglobin concentration, citrate synthase activity, and beta-hydroxyacyl-CoA dehydrogenase was determined for all samples. The swimming muscles of seals had an average total mitochondrial volume density per volume of fiber of 9.7%. The swimming muscles of sea lions and fur seals had average mitochondrial volume densities of 6.2 and 8.8%, respectively. These values were 1.7- to 2.0-fold greater than in the nonswimming muscles. Myoglobin concentration, citrate synthase activity, and beta-hydroxyacyl-CoA dehydrogenase were 1.1- to 2. 3-fold greater in the swimming vs. nonswimming muscles. The swimming muscles of pinnipeds appear to be adapted for aerobic lipid metabolism under the hypoxic conditions that occur during diving. (+info)A direct comparison of the activities of two humanized respiratory syncytial virus monoclonal antibodies: MEDI-493 and RSHZl9. (2/270)
Two humanized monoclonal antibodies, MEDI-493 and RSHZ19, were developed independently as potential improvements over RSV-IGIV for prevention of respiratory syncytial virus (RSV) infection. RSV-IGIV is a polyclonal human antibody preparation for intravenous infusion enriched for RSV neutralizing activity. A phase III clinical trial showed that MEDI-493 significantly reduced hospitalizations due to RSV infection. In a separate trial, RSHZ19 failed to show significant efficacy. In new studies, the in vitro and in vivo activities of MEDI-493 and RSHZ19 were compared to determine whether the different clinical results are related to differences in biologic activity. MEDI-493 was consistently 4- to 5-fold more potent than RSHZ19 in antigen binding, RSV neutralization, and fusion inhibition assays. Although both MEDI-493 and RSHZ19 were effective against A and B subtypes of RSV in the cotton rat model of RSV infection, 2- to 4-fold higher doses of RSHZ19 were required for similar protection. The enhanced activity of MEDI-493 compared with RSHZ19 may, in part, explain its better clinical effect. (+info)Effectiveness of RSVIG prophylaxis and therapy of respiratory syncytial virus in an immunosuppressed animal model. (3/270)
Respiratory syncytial virus (RSV) has emerged as a leading cause of pneumonia, with high mortality, in bone marrow transplant (BMT) recipients, as well as in other profoundly immunocompromised patients, such as myelosuppressed adults with leukemia. We tested the efficacy of immunoglobulin with high anti-RSV neutralizing antibody levels (RSVIG) for prophylaxis and therapy of RSV infection in cotton rats undergoing prolonged immunosuppression with cyclophosphamide. These animals experience persistent infection, a model which is similar to the disease seen in post-BMT humans. Both prophylaxis and therapy reduced pulmonary viral replication over 500-fold to nearly undetectable levels. In animals receiving continual immunosuppression, the use of multiple therapeutic doses of RSVIG was able to prevent rebound viral replication, though virus was not completely eliminated. (+info)Measles virus-induced immunosuppression in cotton rats is associated with cell cycle retardation in uninfected lymphocytes. (4/270)
Measles virus (MV)-induced immune suppression during acute measles often leads to secondary viral, bacterial and parasitic infections which severely complicate the course of disease. Previously, we have shown that cotton rats are a good animal model to study MV-induced immune suppression, where proliferation inhibition after ex vivo stimulation of cotton rat spleen cells is induced by the viral glycoproteins (fusion and haemagglutinin proteins). We have now tested a variety of putative mechanisms of MV-induced immune suppression in this animal model. Proliferation inhibition is not due to fusion mediated by the MV glycoproteins and subsequent lysis of cells. Other putative mechanisms like classical anergy (unresponsiveness towards IL-2) or apoptosis do not seem to play a role in MV-induced immune suppression. In contrast, it was shown that spleen cells from infected animals preferentially accumulate in the G0/G1 phase and progress more slowly through the cell cycle after mitogen stimulation in comparison to cells from non-infected animals. These data indicate a retardation of the cell cycle which is correlated with proliferation inhibition and might have severe consequences in mounting an effective immune response. (+info)Isolation of Borrelia burgdorferi from Neotoma fuscipes, Peromyscus maniculatus, Peromyscus boylii, and Ixodes pacificus in Oregon. (5/270)
The number of Lyme disease cases in Oregon has increased in recent years despite the fact that the pathogen, Borrelia burgdorferi, has never been isolated in the state. Rodent and tick surveys were undertaken in 1997 to isolate and characterize strains of B. burgdorferi from Oregon and to identify potential reservoirs and vectors of Lyme disease. Borrelia burgdorferi was isolated from Neotoma fuscipes, Peromyscus maniculatus, P. boylii, and Ixodes pacificus. Both N. fuscipes and P. maniculatus were infested with I. pacificus and I. spinipalpis. Although I. pacificus infested P. boylii, I. spinipalpis was not found on this rodent, and only 4% of the P. boylii were infected with B. burgdorferi compared with the 19% and 18% infection rates found in N. fuscipes and P. maniculatus, respectively. Variation in the molecular weights of the outer surface proteins A and B were found in these first confirmed isolates of B. burgdorferi from Oregon, as well as truncated forms of outer surface protein B. (+info)Role of the type 5 adenovirus gene encoding the early region 1B 55-kDa protein in pulmonary pathogenesis. (6/270)
Comparison of the inflammatory response of Sigmodon hispidus cotton rats to pulmonary infection with wild-type 5 adenovirus (Ad5) or with a viral mutant, in which the early region 1B gene encoding a 55-kDa protein, Ad5dl110 (dl110), was deleted, indicated that the inflammation in animals infected with dl110 was markedly reduced compared with the inflammation in animals infected with wild-type Ad5, although both viruses replicated to the same extent. Comparable experiments done with C57BL/6 mice yielded identical results, even though only the early phase of gene expression essential for viral replication occurs in mice. Cytokine analysis of infected mouse lungs indicated that tumor necrosis factor-alpha and IL-6 were produced in relatively large quantities in wild-type Ad5-infected mice and at significantly lower levels in dl110-infected mice during the early stages of infection. (+info)Dusky-footed wood rats (Neotoma fuscipes) as reservoirs of granulocytic Ehrlichiae (Rickettsiales: Ehrlichieae) in northern California. (7/270)
Dusky-footed wood rats (Neotoma fuscipes) and Peromyscus sp. mice (P. maniculatus and P. truei) were collected from one site in Placer County, one site in Santa Cruz County, and two sites in Sonoma County in northern California. Serum or plasma samples from 260 rodents were tested for antibodies to the agent of human granulocytic ehrlichiosis. Of these, samples from 25 wood rats (34% of those tested) and 10 (8%) Peromyscus sp. mice were found to be seropositive, but only those from one site. PCR assays targeting the groESL heat shock operon were conducted on all seropositive specimens and a subset of seronegative blood specimens. Ehrlichial DNA was identified in 17 (68%) of the 25 seropositive wood rat blood samples and in 1 of the 10 (10%) Peromyscus sp. specimens. None of 40 seronegative blood samples was PCR positive. Both seropositive and PCR-positive animals were collected during each trapping period. One male tick out of 84 Ixodes pacificus adults collected was PCR positive; samples of Dermacentor occidentalis nymphs and adults were negative. Nucleotide sequences of amplicons from three wood rat blood specimens and from the single PCR-positive tick differed by one and two bases, respectively, from a sequence previously obtained from Ehrlichia equi. At one site in Sonoma County, wood rats had a concurrent high prevalence of seropositivity and PCR positivity, while other sigmodontine rodents collected at the site were only occasionally infected. We suggest that dusky-footed wood rats serve as reservoirs of granulocytic ehrlichial agents in certain areas of northern California. The tick species involved in the transmission of granulocytic ehrlichiae among wood rats remains unknown. (+info)Short report: a focus of Leishmania mexicana near Tucson, Arizona. (8/270)
Twenty-eight white-throated woodrats (Neotoma albigula) collected in Pima County, Arizona were screened for Leishmania using culture and the polymerase chain reaction (PCR). Two rodents were culture positive. Isoenzyme analysis determined the isolates to be Leishmania mexicana. The two culture-positive and four additional rodents were determined to be Leishmania-positive by the PCR. These isolates extend the geographic and ecologic range of enzootic leishmaniasis in the United States and represent a new host record. (+info)Sigmodontinae is a subfamily of rodents, more specifically within the family Cricetidae. This group is commonly known as the New World rats and mice, and it includes over 300 species that are primarily found in North, Central, and South America. The members of Sigmodontinae vary greatly in size and habits, with some being arboreal while others live on the ground or burrow. Some species have specialized diets, such as eating insects or seeds, while others are more generalist feeders. This subfamily is also notable for its high degree of speciation and diversity, making it an interesting subject for evolutionary biologists and ecologists.
I apologize for any confusion, but "Muridae" is not a medical term. It is a taxonomic category in biology, specifically it is a family of rodents that includes mice, rats, hamsters, gerbils, and many other species. If you have any questions about medical terminology or concepts, I would be happy to help with those.
"Rodentia" is not a medical term, but a taxonomic category in biology. It refers to the largest order of mammals, comprising over 40% of all mammal species. Commonly known as rodents, this group includes mice, rats, hamsters, gerbils, guinea pigs, squirrels, prairie dogs, capybaras, beavers, and many others.
While "Rodentia" itself is not a medical term, certain conditions or issues related to rodents can have medical implications. For instance, rodents are known to carry and transmit various diseases that can affect humans, such as hantavirus, leptospirosis, salmonellosis, and lymphocytic choriomeningitis (LCMV). Therefore, understanding the biology and behavior of rodents is important in the context of public health and preventive medicine.
I'm sorry for any confusion, but "South America" is not a medical term. It is a geographical term that refers to the southern portion of the Americas, which is a continent in the Western Hemisphere. South America is generally defined as including the countries of Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Uruguay, and Venezuela, as well as the overseas departments and territories of French Guiana (France), and the Falkland Islands (UK).
If you have any questions related to medical terminology or health-related topics, I would be happy to help answer them for you.
Rodent-borne diseases are infectious diseases transmitted to humans (and other animals) by rodents, their parasites or by contact with rodent urine, feces, or saliva. These diseases can be caused by viruses, bacteria, fungi, or parasites. Some examples of rodent-borne diseases include Hantavirus Pulmonary Syndrome, Leptospirosis, Salmonellosis, Rat-bite fever, and Plague. It's important to note that rodents can also cause allergic reactions in some people through their dander, urine, or saliva. Proper sanitation, rodent control measures, and protective equipment when handling rodents can help prevent the spread of these diseases.