Uncertainties have existed regarding the systematic induction and management of drug-induced diabetes mellitus (DM). Issues have included the optimal route of administration of the drug, methods of reducing drug toxicosis and mortality, how to induce type-1 versus type-2 DM, and how to manage labile DM in rats. In attempting to induce type-1 DM in Sprague-Dawley rats, we classified hyperglycemic animals as having type-1 DM only if their post-treatment blood ketone concentration was high. We found that multiple doses of alloxan led to significantly higher mortality than did a single dose. A single high dose (200 mg/kg of body weight given intraperitoneally) was the best treatment and led to 70% incidence of type-1 DM and only 10% mortality. In contrast, intravenous administration of similar doses was toxic. Assiduous management of alloxan-induced DM is crucial to avoid severe hypoglycemia from massive insulin release and to avoid diabetic ketoacidosis. Frequent glucose monitoring and appropriate administration of carbohydrate and fluids is necessary during this stage. For long-term management, daily administration of long-acting insulin (glargine) appears to be safe and effective. Rapid-acting insulins reduce glucose concentration rapidly, and must be used with caution. If specific precautions are observed, intraperitoneal administration of high-dose alloxan to laboratory rats leads to a condition that closely resembles human type-1 DM.

Simian T-lymphotropic virus type 1 (STLV-1) is a C-type retrovirus of nonhuman primates that is genetically and antigenically related to human T-lymphotropic virus type 1 (HTLV-1). Infection with STLV-1 has been reported in many species of Old World monkeys and apes, including rhesus macaques (Macaca mulatta). Similar to HTLV infection in humans, STLV infection has been associated with T-cell lymphoproliferative disease or lymphoma in a small proportion of infected animals, predominantly African species. There are conflicting reports of T-cell subset alterations in healthy HTLV-1 carriers. To the authors' knowledge, analysis of T-cell subsets in healthy STLV-1 carrier rhesus macaques has not been reported. Subsets of T cells in peripheral blood from healthy, STLV-1-seropositive rhesus macaques (n = 17) and seronegative controls matched for age and sex (n = 17) were determined by use of fluorescence-activated cell sorter analysis. Parameters measured included CD3, CD4, CD8, CD25, CD28, CD38, and HLA-DR cell sets. Significant differences in T-cell subsets or hematologic parameters were not observed between healthy STLV-seropositive and seronegative groups.

We describe a new spontaneous mutation in BALB/c mice that causes abnormal phenotype, such as congenital cataract and microphthalmia. This abnormality was found to be inheritable because offspring with the same abnormality were produced by backcrossing the abnormal male to its normal female parent. Results of various crosses made to determine the mode of inheritance indicated that this abnormality is attributable to mutation of an autosomal recessive gene. Slit lamp examination of the mutant eyes revealed total lenticular opacity, disturbed typical iris pattern, and abnormal pupillary muscle development. Histologic changes in mutant eyes between gestation day 13 and postnatal day 1 indicated various eye and lens abnormalities, including microphthalmia; underdeveloped iris, optic stalk, cornea, and retina; degenerated lens fibers with lost fibrillar structure; and vacuoles of various sizes at the posterior border of the lens. Mild opacity of the lens was found to progress with age and became denser, resembling mature cataract, and occupying the lens completely at the age of six to eight weeks. We, therefore, temporarily designated this abnormality as dense cataract and microphthalmia, with the gene symbol dcm.

Phenotypic and biological heterogeneity was studied in a single transgenic mouse model to determine the level of biological variance. We analyzed 1,258 tumors from 417 MMTV-wt-ErbB-2 transgenic mice, subdivided by casein or soy-based dietary randomization and hormonal treatment. Variance in tumor histologic features, growth pattern, invasion, metastases, and multi-focality were detected in untreated and treated mice. Ninety-three percent (1,174/1,258) of tumors had the solid growth pattern widely reported in this model. However, among the solid tumors, a spectrum of growth patterns, from well-circumscribed tumors with a pseudocapsule to locally invasive or highly aggressive, metastatic subtype, was observed. Of the non-solid tumors, glandular features were prominent in 84 (7%). Adenocarcinomas included papillary, acinar/glandular, and adenosquamous subtypes. Adenosquamous tumors were exclusively observed in the group of mice treated on a short-term basis with estrogen. In contrast to the reported literature for this transgenic mouse model, mammary tumors were multifocal in the majority of cases (303 of 417 mice, or 73%). Results of this extensive study of a single transgenic model of mammary tumorigenesis indicate phenotypic and biological heterogeneity not previously associated with this transgenic mouse. These data support a complex, multistep process of carcinogenesis and clonal evolution, with biological and phenotypic variance similar to that observed in human mammary cancer development.

Lactate dehydrogenase-elevating virus (LDEV) induces persistent infections in laboratory mice, alters in vivo physiology, and is a common contaminant of biological materials such as transplantable tumor cell lines. The fluorogenic nuclease reverse transcriptase polymerase chain reaction (fnRT-PCR) assay combines RT-PCR analysis with an internal fluorogenic hybridization probe, thereby eliminating post-PCR processing and potentially enhancing specificity. An fnRT-PCR assay specific for LDEV was therefore developed by targeting primer and probe sequences to a unique region of the LDEV nucleocapsid (VP1) gene. Using the LDEV fnRT-PCR assay, we detected only LDEV and did not detect other RNA viruses that are capable of naturally infecting rodents. Using this assay, we detected as little as 10 fg of LDEV RNA; the assay was 10-fold less sensitive when directly compared with the mouse bioassay (measurement of serum LD after inoculation), without the problematic false-positive serum LD enzyme elevations associated with the mouse bioassay. Using the fnRT-PCR assay, we also were able to detect viral RNA in numerous tissues and in feces collected from experimentally inoculated C3H/HeN mice, but we did not detect any viral RNA in similar samples collected from age- and strain-matched mock-infected mice. Finally, using the fnRT-PCR assay, we were able to detect LDEV RNA in biological samples that had previously been determined to be contaminated with LDEV by use of the mouse bioassay and an RT-PCR assay at another laboratory. In conclusion, the LDEV fnRT-PCR assay is a potentially high-throughput diagnostic assay for detection of LDEV in mice and contaminated biological materials.

Buprenorphine has been widely recommended for treatment of pain in rodents. We have previously documented that the recommended postoperative oral dose of buprenorphine in male Long-Evans rats, 0.5 mg/kg, is not as effective as the recommended parenteral dose of buprenorphine (0.05 mg/kg, s.c.) as an analgesic (21). In the series of experiments reported here, we compared: the analgesic effect of buprenorphine when prepared in two ways in the laboratory with that of a commercially available injectable solution of buprenorphine; the analgesic effect of buprenorphine in Long-Evans rats with that in Sprague-Dawley rats; and Long-Evans and Sprague-Dawley rats for development of pica, a commonly reported side effect of buprenorphine. We followed the pica experiment with assessment of the effectiveness of buprenorphine in establishing a conditioned flavor aversion. The results indicated that method of preparation did not result in any significant differences in the efficacy of injected buprenorphine. Strain of rat was not associated with a significant difference in the efficacy of buprenorphine. However, a significant strain difference was found in development of pica. Buprenorphine treatment was effective in inducing a conditioned flavor aversion. We concluded that the recommended oral dose of buprenorphine (0.5 mg/kg) is ineffective as an analgesic, and that this was not the result of method of preparation of the buprenorphine or strain of rat used. Furthermore, we concluded that buprenorphine treatment may induce gastrointestinal distress in both strains tested. The results reaffirm our previous conclusion that oral administration of buprenorphine at 0.5 mg/kg, despite the general recommendation, is not a reasonable treatment for postsurgical pain in rats.

Helicobacter hepaticus is a bacterial pathogen of mice that has been reported to cause chronic intestinal inflammation in A/JCr, germfree Swiss Webster, and immunodeficient mice. To the authors' knowledge, the influence of sex on development of chronic intestinal inflammation in H. hepaticus-infected mice has not been investigated. The purposes of the study reported here were to determine whether severity of intestinal inflammation differs between male and female A/JCr mice chronically infected with H. hepaticus and to characterize the mucosal immune response in these mice. The cecum of male and female A/JCr mice infected with H. hepaticus for 1 month and 3 months was objectively evaluated histologically for intestinal disease. Also, semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was done to measure interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), interleukin 4 (IL-4), IL-10, macrophage inflammatory protein-1α (MIP-1α), interferon-inducible protein of 10 kDa (IP-10), and monokine induced by gamma interferon (MIG) mRNA values in the cecal tissue of these mice. Significant differences in cecal lesion scores were not present at 1 month after infection. However, infected female mice had significantly up-regulated expression of cecal IL-10, MIP-1α, IP-10, and MIG mRNA compared with that in uninfected females, and expression of IL-10 and MIP-1α was significantly greater than that detected in infected male mice (P ≤ 0.05). At 3 months after infection, cecal lesion scores were significantly (P ≤ 0.05) increased in female and male mice compared with uninfected controls, and infected female mice had significantly (P ≤ 0.05) higher cecal lesion scores than did infected male mice. In addition, infected females had significant (P ≤ 0.05) increases in cecal IFN-γ, TNF-α, IL-10, MIP-1α, IP-10, and MIG mRNA values compared with values in uninfected females and infected males, and male mice had significant (P ≤ 0.05) increases in cecal TNF-α and IL-10 mRNA values compared with those for male control mice. These data indicate that, in H. hepaticus-infected A/JCr mice, females develop more severe intestinal inflammation than do males, and the chronic mucosal inflammation is polarized toward a Th1 response that is not down-regulated by increased activity of IL-10. We propose that H. hepaticus-infected A/JCr mice will serve as a good animal model with which to study the influence of sex on bacterial-induced mucosal inflammation.

A nontuberculous Mycobacterium ulcerans-like organism was identified as the causative agent of an epizootic of mycobacteriosis in a colony of African tropical clawed frogs, Xenopus (Silurana) tropicalis, at the University of California, Berkeley. Diverse clinical signs of disease were observed, including lethargy, excess buoyancy, coelomic effusion, cutaneous ulcers, and granulomas. Visceral granulomas, ulcerative and granulomatous dermatitis, coelomitis, and septicemia were common findings at necropsy. Identification of M. ulcerans-like organisms was based on molecular and phenotypical characteristics. The findings of this investigation indicate that this M. ulcerans-like organism is a primary cause of morbidity and mortality in aquatic anurans and should be considered in the differential diagnosis of coelomic effusion in amphibians. Furthermore, if this Mycobacterium species ultimately is identified as M. ulcerans, X. tropicalis should be considered a potential source of this important public health pathogen.

A high frequency of struvite urolithiasis, hydronephrosis, and other urinary tract lesions developed in a group of Lewis rats inoculated intracranially with lymphocytic choriomeningitis virus (LCMV). Initially, clinically ill rats were referred to necropsy: 30 rats over 3 years. These rats had high frequency of urolithiasis (8/30, 27%), hydronephrosis (12/30, 40%), cystitis (9/30, 30%), transitional cell carcinoma (4/30, 13%), and pyelonephritis (19/30, 63%). Lesions were more common in LCMV-inoculated rats. After this trend was noted, all rats on this protocol were necropsied as part of a cohort study (n = 144). Although the apparent frequency of disease was lower due to increased sampling, there still was a high number of urolithiasis (9/144, 6%) and hydronephrosis (40/144, 28%) cases. All cases of urolithiasis developed in rats inoculated with LCMV (9/44, 20%), as did most cases of hydronephrosis (31/44, 70%). Although sham-injected and uninoculated control rats also had high frequency of hydronephrosis (6/57 [11%] and 3/43 [7%], respectively), LCMV-inoculated rats had a significantly higher frequency of disease than did sham inoculated (P < 0.0001) and uninoculated (P < 0.0001) controls. These results suggest that Lewis rats may be predisposed to developing lesions of the urinary tract, and that intracranial inoculation of rats with LCMV augments this tendency, leading to formation of struvite calculi and associated urinary tract disease.

Following short-term signs of weakness, depression, and/or anorexia of less than 24 h, two adult male African green monkeys (Cercopithecus aethiops sabeus) of St. Kitts origin died from complications of cecal volvulus. Gaseous distention was radiologically apparent in one animal. Necropsy of both monkeys revealed cecal volvulus, one at the ileocecal junction and one involving a segment of the distal portion of the ileum and cecum. Congestion and hemorrhage were evident microscopically in the lamina propria of the affected intestine, with variable necrosis.

A diagnosis of glioblastoma multiforme (GBM) was made for cerebral masses found at necropsy in two baboons (Papio cynocephalus anubis). Case 1 was an adult (6.18 years old) male baboon that suddenly died during a physical examination as part of a clinical evaluation for a leg lameness. Case 2 was an adult (5.95 years old) female baboon that stopped breathing during anesthesia for an magnetic resonance imaging to evaluate lethargy, weight loss, inappetence, and dilated pupils. Both animals had undergone total body irradiation with cobalt during a research protocol. The incidence of spontaneous brain tumors in nonhuman primates is low, but radiation-induced GBM lesions in rhesus macaques (Macaca mulatta) have been reported. A definitive diagnosis was made in these cases, using histopathologic criteria of cellular pleomorphism, high mitotic rate, regions of coagulation necrosis, and endothelial proliferation.

We present the first, to our knowledge, described case of carcinosarcoma of the maxilla in a squirrel monkey. Carcinosarcomas are rare tumors of the upper aerodigestive tract, and consist of carcinomatous and sarcomatous tissue. Histologic analysis revealed a neoplasm composed of an adenocarcinomatous component (epithelial element) and a mesenchymal component (sarcomatous element). Metastatic growth was documented in the lung tissue and the submandibular lymph node. The histolopathologic findings, the pattern of metastasis, and the clinical progression closely resembled those of carcinosarcoma involving salivary glands in humans.