Nuclear Magnetic Resonance Signature of the Spin-Nematic Phase in LiCuVO_{4} at High Magnetic Fields.

We report a ^{51}V nuclear magnetic resonance investigation of the frustrated spin-1/2 chain compound LiCuVO_{4}, performed in pulsed magnetic fields and focused on high-field phases up to 56 T. For the crystal orientations H∥c and H∥b, we find a narrow field region just below the magnetic saturation where the local magnetization remains uniform and homogeneous, while its value is field dependent. This behavior is the first microscopic signature of the spin-nematic state, breaking spin-rotation symmetry without generating any transverse dipolar order, and is consistent with theoretical predictions for the LiCuVO_{4} compound.

Polyomavirus-associated nephritis in 2 horses.

Polyomaviruses produce latent and asymptomatic infections in many species, but productive and lytic infections are rare. In immunocompromised humans, polyomaviruses can cause tubulointerstitial nephritis, demyelination, or meningoencephalitis in the central nervous system and interstitial pneumonia. This report describes 2 Standardbred horses with tubular necrosis and tubulointerstitial nephritis associated with productive equine polyomavirus infection that resembles BK polyomavirus nephropathy in immunocompromised humans.

Rapid decreases in salinity, but not increases, lead to immune dysregulation in Nile tilapia, Oreochromis niloticus (L.).

Rapid changes in salinity, as with other environmental stressors, can have detrimental effects on fish and may trigger increased susceptibility to disease. However, the precise mechanisms of these effects are not well understood. We examined the effects of sudden increases or decreases in salinity on teleost immune function using Nile tilapia, Oreochromis niloticus (L.), as the fish model in a battery of bioassays of increasing immune system specificity. Two different salinity experiments were performed: one of increasing salinity (0 to 5, 10 and 20 g L(-1) ) and one of decreasing salinity (20 to 15, 10 and 5 g L(-1) ). Histopathology of anterior kidney, gills, gonads, intestines and liver of exposed fish was performed, but no remarkable lesions were found that were attributable to the salinity treatment regimes. The spleen was removed from each fish for analysis of cytokine expression, and peripheral blood was used for haematology, cortisol and phagocytosis assays. In the increasing salinity experiments, no significant changes were observed in any immune system assays. However, in the decreasing salinity experiments, lymphopenia, neutrophilia and monocytosis were observed in the peripheral blood without modification of the packed cell volume, plasma protein or plasma cortisol levels. Phagocytosis was increased in response to decreases in salinity from 20 g L(-1) to 15 g L(-1) , 10 g L(-1) and 5 g L(-1) , whereas phagocytic index was not significantly altered. Transforming growth factor-ß (TGF-ß) transcription increased during the same decreases in salinity. However, the TGF-ß value at 5 g L(-1) was less than those in the 15 and 10 g L(-1) salinity treatments. Interleukin-1ß (IL-1ß) transcription did not significantly respond to either salinity regime. In total, acute salinity changes appeared to trigger reactive dysregulation of the immune response in tilapia, a situation which, when combined with additional co-occurring stressors such as sudden changes in temperature and/or dissolved oxygen, could make fish more susceptible to infectious diseases. Accordingly, these findings may help to explain how sudden environmental changes may initiate disease outbreaks and lead to critical declines in cultured or wild fish populations.

Evidence of a bond-nematic phase in LiCuVO4.

Polarized and unpolarized neutron scattering experiments on the frustrated ferromagnetic spin-1/2 chain LiCuVO4 show that the phase transition at H(Q) of 8 T is driven by quadrupolar fluctuations and that dipolar correlations are short range with moments parallel to the applied magnetic field in the high-field phase. Heat-capacity measurements evidence a phase transition into this high-field phase, with an anomaly clearly different from that at low magnetic fields. Our experimental data are consistent with a picture where the ground state above H(Q) has a next-nearest neighbor bond-nematic order along the chains with a fluidlike coherence between weakly coupled chains.

Neoplastic and nonneoplastic liver lesions induced by dimethylnitrosamine in Japanese medaka fish.

Small fish models have been used for decades in carcinogenicity testing. Demonstration of common morphological changes associated with specific mechanisms is a clear avenue by which data can be compared across divergent phyletic levels. Dimethylnitrosamine, used in rats to model human alcoholic cirrhosis and hepatic neoplasia, is also a potent hepatotoxin and carcinogen in fish. We recently reported some striking differences in the mutagenicity of DMN in lambda cII transgenic medaka fish vs. Big Blue(®) rats, but the pre-neoplastic and neoplastic commonalities between the two models are largely unknown. Here, we focus on these commonalities, with special emphasis on the TGF-ß pathway and its corresponding role in DMN-induced hepatic neoplasia. Similar to mammals, hepatocellular necrosis, regeneration, and dysplasia; hepatic stellate cell and "spindle cell" proliferation; hepatocellular and biliary carcinomas; and TGF-ß1 expression by dysplastic hepatocytes all occurred in DMN-exposed medaka. Positive TGF-ß1 staining increased with increasing DMN exposure in bile preductular epithelial cells, intermediate cells, immature hepatocytes and fewer mature hepatocytes. Muscle specific actin identified hepatic stellate cells in DMN-exposed fish. Additional mechanistic comparisons between animal models at different phyletic levels will continue to facilitate the interspecies extrapolations that are so critical to toxicological risk assessments.

Operative factors associated with short-term outcome in horses with large colon volvulus: 47 cases from 2006 to 2013.

REASONS FOR PERFORMING STUDY: There is an important need for objective parameters that accurately predict the outcome of horses with large colon volvulus. OBJECTIVES: To evaluate the predictive value of a series of histomorphometric parameters on short-term outcome, as well as the impact of colonic resection on horses with large colon volvulus. STUDY DESIGN: Retrospective cohort study. METHODS: Adult horses admitted to the Equine and Farm Animal Veterinary Center at North Carolina State University, Peterson and Smith and Chino Valley Equine Hospitals between 2006 and 2013 that underwent an exploratory coeliotomy, diagnosed with large colon volvulus of ≥360 degrees, where a pelvic flexure biopsy was obtained, and that recovered from general anaesthesia, were selected for inclusion in the study. Logistic regression was used to determine associations between signalment, histomorphometric measurements of interstitium-to-crypt ratio, degree of haemorrhage, percentage loss of luminal and glandular epithelium, as well as colonic resection with short-term outcome (discharge from the hospital). RESULTS: Pelvic flexure biopsies from 47 horses with large colon volvulus were evaluated. Factors that were significantly associated with short-term outcome on univariate logistic regression were Thoroughbred breed (P = 0.04), interstitium-to-crypt ratio >1 (P = 0.02) and haemorrhage score ≥3 (P = 0.005). Resection (P = 0.92) was not found to be associated significantly with short-term outcome. No combined factors increased the likelihood of death in forward stepwise logistic regression modelling. A digitally quantified measurement of haemorrhage area strengthened the association of haemorrhage with nonsurvival in cases of large colon volvulus. CONCLUSIONS: Histomorphometric measurements of interstitium-to-crypt ratio and degree of haemorrhage predict short-term outcome in cases of large colon volvulus. Resection was not associated with short-term outcome in horses selected for this study. Accurate quantification of mucosal haemorrhage at the time of surgery may improve veterinary surgeons' prognostic capabilities in horses with large colon volvulus.

Key metabolites in tissue extracts of Elliptio complanata identified using (1)H nuclear magnetic resonance spectroscopy.

We used (1)H nuclear magnetic resonance spectroscopy to describe key metabolites of the polar metabolome of the freshwater mussel, Elliptio complanata. Principal components analysis documented variability across tissue types and river of origin in mussels collected from two rivers in North Carolina (USA). Muscle, digestive gland, mantle and gill tissues yielded identifiable but overlapping metabolic profiles. Variation in digestive gland metabolic profiles between the two mussel collection sites was characterized by differences in mono- and disaccharides. Variation in mantle tissue metabolomes appeared to be associated with sex. Nuclear magnetic resonance spectroscopy is a sensitive means to detect metabolites in the tissues of E. complanata and holds promise as a tool for the investigation of freshwater mussel health and physiology.

Evidence of genetic recombination in Leishmania.

In the genus Leishmania there has been no convincing demonstration of genetic exchange, and it has been proposed that reproduction is clonal. However, preliminary characterization of two strains of Leishmania isolated from wild animals in a zoonotic focus of cutaneous leishmaniasis in the Eastern Province of Saudi Arabia, has suggested that they may represent hybrids of Leishmania major and Leishmania arabica. Evidence presented here strongly supports this hypothesis. Isoenzyme analysis and molecular karyotyping of cloned organisms indicated that the putative hybrids are distinct from other species of Leishmania, and possess characteristics of both L. major and L. arabica. Experiments using highly specific probes demonstrated that kinetoplast minicircle DNA from the putative hybrid contained L. major-specific, but not L. arabica-specific sequences. DNA fingerprinting data obtained using 6 genomic DNA probes were consistent in all cases with a L. major/L. arabica recombinant genotype, and implied both diploidy and allelic segregation. These observations suggest that sexual reproduction may generate genetic diversity within natural Leishmania populations.

The dramatic presentation of colonic lipomata: report of two cases and review of the literature.

Colonic lipoma with a dramatic presentation requiring urgent operation is a rare occurrence. We report two such cases in conjunction with a review of the literature on colonic lipomata. Clinicopathologic features of two patients who required urgent resection were studied. The preoperative diagnosis of colonic lipoma was suggested on imaging study in one case. A MEDLINE search was conducted with a special goal of revealing cases with a dramatic presentation. One patient presented with rectal bleeding and intussusception related to a partially infarcted 4.5-cm submucosal lipoma of the lower descending colon. The second patient presented with intestinal obstruction related to a near-totally infarcted 6-cm submucosal lipoma at the splenic flexure. In both cases a florid reactive vascular and fibro-/myofibroblastic proliferation and associated hyperplastic mucosal pattern were present at the base and edge of the lipoma. Among 275 previously reported cases of colonic lipoma 28 patients had a dramatic presentation with pain and/or rectal bleeding being the most significant prodromal symptom. In this subset the lipomas tended to be larger, frequently had associated marked necrosis/ulceration, and were less likely to be located in the ascending colon/cecum. Whereas colonic lipomas are relatively common occasional cases present dramatically with massive bleeding, intussusception, or even perforation for which emergency operation is required. Such lipomas usually reveal marked ischemic changes.

Mechanistic considerations in small fish carcinogenicity testing.

Historically, small fish species have proven useful both as environmental sentinels and as versatile test animals in toxicity and carcinogenicity bioassays. They can be bred in large numbers, have low maintenance and bioassay costs, and have a low background incidence of tumors. However, more mechanistic information is needed to help validate the information garnered from these models and to keep pace with other more fully developed animal models. This paper focuses on mechanistic considerations when using small fish models for carcinogenicity testing. Several small aquarium fish species have proven useful. The Japanese medaka is perhaps the best characterized small fish model for carcinogenicity testing; however, the zebrafish is emerging as an important model because it is well characterized genetically. Both route and methodology of exposure may affect the outcome of the study. Most studies have been conducted by introducing the test compound into the ambient water, but dietary exposures and embryo microinjection have also been used. Other considerations in study design include use of an initiating carcinogen, such as diethlynitrosamine, and differences in xenobiotic metabolism, such as the fact that fish CYP2B is refractory to phenobarbital induction. The small size of these models has perhaps limited some types of mechanistic studies, such as formation and repair of DNA adducts in response to carcinogen exposure. However, improved analytical methods are allowing greater resolution and should be applied to small fish species. Slide-based methods such as immunohistochemistry are an important adjunct to routine histopathology and should be included in study design. However, there is a need for development of more species-specific antibodies for fish research. There is also a need for more fish-specific data on cytokines, serum biochemistry, and oncogenes to strengthen the use of these important test models.

Verminous encephalitis apparently caused by the filarioid nematode Chandlerella quiscali in emus (Dromaius novaehollandiae).

Verminous encephalitis attributed to Chandlerella quiscali was diagnosed in a flock of emus (Dromaius novaehollandiae). Clinically affected birds showed torticollis and progressive ataxia. Filarioid parasites with morphological characteristics resembling C. quiscali were identified in one case. Histologic lesions in the brain and spinal cord consisted of mild to moderate perivascular cuffing and scattered areas of variable mild necrosis. Parasites observed within the parenchyma of the brain and spinal cord often were not associated with either necrosis or an inflammatory reaction. Ivermectin administered subcutaneously at 4-week intervals at a dose rate of 200 micrograms/kg body weight appeared to prevent clinical signs in flocks in the presumed endemic area.

Chlamydiosis in commercial rheas (Rhea americana).

Mild to marked splenomegaly was observed in three of four rheas that died acutely in three unrelated commercial ratite facilities in Southeastern Louisiana. Mortalities occurred within a 5-week period in birds ranging from 2 months to 3 years of age. Multifocal hepatic and splenic necrosis with mononuclear cell infiltrates, typical of chlamydiosis in other avian species, was present on histopathologic sections. The diagnoses were confirmed by demonstration of inclusion bodies in splenic impression smears and fluorescent-antibody testing performed on Vero cell cultures.

Hepatocarcinogenesis in western mosquitofish (Gambusia affinis) exposed to methylazoxymethanol acetate.

To assess the potential of western mosquitofish (Gambusia affinis) for the detection of environmental carcinogens, laboratory-reared specimens were exposed to methylazoxymethanol acetate 10 mg per 1 for 2 h and then examined periodically for the onset of neoplastic lesions. Approximately 33 per cent of the exposed fish developed liver neoplasms within 25 weeks of exposure and 52 per cent within 40 weeks. The lesions were mostly hepatocellular carcinomas and cholangiocarcinomas. No neoplastic lesions were detected in other organs. The carcinogen sensitivity and the widespread distribution of the mosquitofish suggest that this species would be useful as a warm water sentinel for environmental contamination.

Experimental infection of cats with Tritrichomonas foetus.

OBJECTIVE: To determine whether infection with Tritrichomonas foetus causes diarrhea in specific-pathogen-free or Cryptosporidium coinfected cats. ANIMALS: 4 cats with subclinical cryptosporidiosis (group 1) and 4 specific-pathogen-free cats (group 2). PROCEDURE: Cats were infected orogastrically with an axenic culture of T. foetus isolated from a kitten with diarrhea. Direct microscopy and protozoal culture of feces, fecal character, serial colonic mucosal biopsy specimens, and response to treatment with nitazoxanide (NTZ; group 1) or prednisolone (groups 1 and 2) were assessed. RESULTS: Infection with T. foetus persisted in all cats for the entire 203-day study and resulted in diarrhea that resolved after 7 weeks. Group-1 cats had an earlier onset, more severe diarrhea, and increased number of trichomonads on direct fecal examination, compared with group-2 cats. Use of NTZ eliminated shedding of T. foetus and Cryptosporidium oocysts, but diarrhea consisting of trichomonad-containing feces recurred when treatment was discontinued. Prednisolone did not have an effect on infection with T. foetus but resulted in reappearance of Cryptosporidium oocysts in the feces of 2 of 4 cats. During necropsy, T. foetus was isolated from contents of the ileum, cecum, and colon. Tritrichomonas foetus organisms and antigen were detected on surface epithelia and within superficial detritus of the cecal and colonic mucosa. CONCLUSIONS AND CLINICAL RELEVANCE: After experimental inoculation in cats, T. foetus organisms colonize the ileum, cecum, and colon, reside in close contact with the epithelium, and are associated with transient diarrhea that is exacerbated by coexisting cryptosporidiosis but not treatment with prednisolone.

The effect of tramadol and indomethacin coadministration on gastric barrier function in dogs.

BACKGROUND: Tramadol is a centrally acting analgesic that is often used in conjunction with nonsteroidal anti-inflammatory drugs (NSAIDs). The effect of coadministration of tramadol and indomethacin on gastric barrier function in dogs is unknown. HYPOTHESIS/OBJECTIVES: That coadministration of a nonselective NSAID (indomethacin) and tramadol would decrease recovery of barrier function as compared with acid-injured, indomethacin-treated, and tramadol-treated mucosa. ANIMALS: Gastric mucosa of 10 humanely euthanized shelter dogs. METHODS: Ex vivo study. Mounted gastric mucosa was treated with indomethacin, tramadol, or both. Gastric barrier function, prostanoid production, and cyclooxygenase expression were quantified. RESULTS: Indomethacin decreased recovery of transepithelial electrical resistance after injury, although neither tramadol nor the coadministration of the two had an additional effect. Indomethacin inhibited production of gastroprotective prostanoids prostaglandin E2 (acid-injured PGE2 : 509.3 ± 158.3 pg/mL, indomethacin + acid injury PGE2 : 182.9 ± 93.8 pg/mL, P < .001) and thromboxane B2 (acid-injured TXB2 : 233.2 ± 90.7 pg/mL, indomethacin + acid injury TXB2 : 37.9 ± 16.8 pg/mL, P < .001), whereas tramadol had no significant effect (PGE2 P = .713, TXB2 P = .194). Neither drug had an effect on cyclooxygenase expression (COX-1 P = .743, COX-2 P = .705). Acid injury induced moderate to marked epithelial cell sloughing, which was unchanged by drug administration. CONCLUSIONS AND CLINICAL IMPORTANCE: There was no apparent interaction of tramadol and a nonselective cyclooxygenase in this ex vivo model. These results suggest that if there is an adverse interaction of the 2 drugs in vivo, it is unlikely to be via prostanoid inhibition.

Padé approximations for the magnetic susceptibilities of Heisenberg antiferromagnetic spin chains for various spin values.

The temperature dependence of the spin susceptibilities of S = 1, 3/2, 2, 5/2 and 7/2 Heisenberg antiferromagnetic 1D spins chains with nearest-neighbor coupling was simulated via quantum Monte Carlo calculations, within the reduced temperature range of 0.005 ≤ T* ≤ 100, and fitted to a Padé approximation with deviations between the simulated and fitted data of the same order of magnitude as or smaller than the quantum Monte Carlo simulation error. To demonstrate the practicality of our theoretical findings, we compare these results with the susceptibility of the well known 1D chain compound TMMC ([(CH(3))(4)N[MnCl(3)]], d(5), S = 5/2) and find that different intra-chain spin-exchange parameters result if we consider the data above and below the structural phase transition reported for TMMC at ~126 K. The structural phase transition, which gives rise to an anomaly in the magnetic susceptibility, is independent of the magnetic field up to magnetic fields of 7 T. Additionally, we show that the S = 1 system NiTa(2)O(6) with tri-rutile crystal structure can be very well described as a Heisenberg S = 1 spin chain.

Immunohistochemical characterization of the hepatic progenitor cell compartment in medaka (Oryzias latipes) following hepatic injury.

Laboratory fish species are used increasingly in biomedical research and are considered robust models for the study of regenerative processes. Studies investigating the response of the fish liver to injury have demonstrated the presence of a ductular reaction and oval-like cells in injured and regenerating liver. To date, however, it is unclear if this cell population is the piscine equivalent of oval cells (OCs) or intermediate hepatobiliary cells (IHBCs) identified in rodents and man, respectively. The present study defines the process of OC differentiation in fish liver using histopathology, immunohistochemistry and transmission electron microscopy. To generate OC proliferation in Japanese medaka (Oryzias latipes), hepatic injury was induced by exposure of adult fish to either microcystin LR or dimethylnitrosamine. A transgenic strain of medaka expressing a red fluorescent protein (RFP) exclusively in hepatocytes was used. The morphological response to injury was characterized by a ductular reaction comprised of cytokeratin (CK) AE1/AE3(+) OCs progressing to IHBCs variably positive for CK and RFP and finally mature RFP(+) hepatocytes and CK(+) cholangiocytes. These observations support a bipotential differentiation pathway of fish OCs towards hepatocytes and cholangiocytes. Ultrastructural morphology confirmed the presence of OCs and differentiation towards hepatocytes. These results demonstrated clear similarities between patterns of reaction to injury in fish and mammalian livers. They also confirm the presence of, and support the putative bipotential lineage capabilities of, the fish OC.