Extraventricular neurocytoma of the spinal cord in a dog

Central neurocytoma is a rare, prognostically favorable neuronal tumor of the human central nervous system, typically located intraventricularly near the foramen of Monro. Extraventricular cerebral neurocytomas and spinal tumors have also been reported. To date, however, neurocytomas have not been documented in domestic animal species. In this report, we describe a spinal cord tumor in a dog. The microscopic examination revealed tumor cells forming loosely packed clusters in some areas and palisades in other areas. In addition, they showed fine fibrillary neuropil-like areas of different sizes, sometimes resembling the "rosettes" of pineocytomas, as well as ependymoma-like perivascular pseudorosettes. The tumor cells had scant eosinophilic cytoplasm, with perinuclear halos, closely resembling the appearance of oligodendroglioma. Immunohistochemical staining showed expression of synaptophysin and neuron-specific enolase by tumor cells and pronounced in fibrillary areas. On the basis of histomorphology and immunohistochemical reactivity, the present tumor was diagnosed as extraventricular neurocytoma.     

Influence of Inseminate Components on Porcine Leucocyte Migration In Vitro and In Vivo after Pre- and Post-Ovulatory Insemination

A post‐breeding migration of leucocytes (PMN) into the uterus is considered to be an important reason for sperm losses. Minimizing such effects may be necessary for successful insemination with low sperm numbers, as required with sex‐sorted spermatozoa. We examined the magnitude of PMN influx 3 h after pre‐ or post‐ovulatory insemination with various combinations of seminal plasma (SP), semen extender Androhep? (AH; Minitüb, Tiefenbach, Germany) and sperm preparations (S). Pre‐ovulatory inseminations with preparations containing 98% AH caused a massive influx of PMN, independent of whether spermatozoa were present (628 ± 189 × 10⁶ leucocytes/uterine horn) or not (580 ± 153 × 10⁶). Post‐ovulatory, 98% AH caused a comparable immigration only in the absence of sperm cells (AH: 569 ± 198 × 10⁶, AH+S: 162 ± 102 × 10⁶). The presence of SP significantly dampened the numbers of recruited uterine leucocytes. The reaction to all inseminates containing 98% SP both with and without spermatozoa, used before ovulation (SP: 14 ± 6 × 10⁶, SP+S: 73 ± 27 × 10⁶) and after ovulation (SP: 60 ± 32 × 10⁶, SP+S: 51 ± 33 × 10⁶) did not differ significantly from controls using phosphate buffered saline (PBS) (pre‐ovulatory: 1 ± 1 × 10⁶, post‐ovulatory: 11 ± 9 × 10⁶). Quantitative in vitro transmigration assays with blood‐derived PMN proved that AH‐induced leucocyte migration into the uterus to be not as a result of direct chemotaxis, because, on account of the chelator citrate, AH significantly inhibited the transmigration towards recombinant human Interleukin‐8 (rhCXCL8) (AH: 14 ± 5% migration rate vs controls: 37 ± 6%, p < 0.05). Supernatants of spermatozoa incubated in PBS for 1, 12 or 24 h showed neither chemoattractive nor chemotaxis‐inhibiting properties. SP at ≥0.1% [v/v] significantly inhibited the in vitro transmigration of PMN. With respect to in vivo migration of neutrophils, the striking difference in the results between semen extender and seminal plasma suggests that adaptation of extender composition is needed to reflect more closely the in vivo regulatory potential of natural seminal plasma.     

The increasing scarcity of red oaks in Mississippi River floodplain forests: Influence of the residual overstory

Red oaks – cherrybark oak (Quercus pagoda Raf.), willow oak (Quercus phellos L.), water oak (Quercus nigra L.), and Nuttall oak (Quercus texana Buckley; aka: Quercus nuttallii Palmer) – are not regrowing in Mississippi Delta river floodplain forests in the southeastern United States in sufficient numbers to sustain the former species composition and timber and wildlife values. Even if vigorous red oak reproduction becomes established, partial harvesting that does not remove the taller trees will suppress understory red oak height growth more than it will suppress height growth of such other species as sugarberry (Celtis laevigata Willd.), American elm (Ulmus americana L.), cedar elm (Ulmus crassifolia Nutt.), swamp dogwood (Cornus foemina Mill.), green ash (Fraxinus pennsylvanica Marshall), and sweetgum (Liquidambar styraciflua L.). Consequently, the red oaks in these partially harvested stands become increasingly suppressed and probably die; and there is a shift in species composition to the other species. In addition to ensuring vigorous oak reproduction, silvicultural clearcutting or rapid removal of the residual trees following shelterwood or seed tree harvesting to provide full sunlight is needed to ensure red oaks become a dominant part of these future river floodplain stands.     

Coincident scrapie infection and nephritis lead to urinary prion excretion

Prion infectivity is typically restricted to the central nervous and lymphatic systems of infected hosts, but chronic inflammation can expand the distribution of prions. We tested whether chronic inflammatory kidney disorders would trigger excretion of prion infectivity into urine. Urinary proteins from scrapie-infected mice with lymphocytic nephritis induced scrapie upon inoculation into noninfected indicator mice. Prionuria was found in presymptomatic scrapie-infected and in sick mice, whereas neither prionuria nor urinary PrP(Sc) was detectable in prion-infected wild-type or PrP(C)-overexpressing mice, or in nephritic mice inoculated with noninfectious brain. Thus, urine may provide a vector for horizontal prion transmission, and inflammation of excretory organs may influence prion spread.     

Adrenocorticotropic hormone, but not trilostane, causes severe adrenal hemorrhage, vacuolization, and apoptosis in rats

Adrenal necrosis has been reported as a complication of trilostane application in dogs with hyperadrenocorticism. One suspicion was that necrosis results from the increase of adrenocorticotropic hormone (ACTH) during trilostane therapy. The aim of the current study was to assess the effects of ACTH and trilostane on adrenal glands of rats. For experiment 1, 36 rats were divided into 6 groups. Groups 1.1 to 1.4 received ACTH in different doses (60, 40, 20, and 10 μg/d) infused subcutaneously with osmotic minipumps for 16 wk. Group 1.5 received saline, and group 1.6 received no therapy. For experiment 2, 24 rats were divided into 3 groups. Group 2.1 and 2.2 received 5 and 50 mg/kg trilostane/d orally mixed into chocolate pudding for 16 wk. Eight control rats received pudding alone. At the end of the experiments, adrenal glands were assessed for necrosis by histology and immunohistochemistry; levels of endogenous ACTH and nucleosomes were assessed in the blood. Rats treated with 60 μg ACTH/d showed more hemorrhage and vacuolization and increased numbers of apoptotic cells in the adrenal glands than rats treated with 20 or 10 μg ACTH/d, trilostane, or control rats. Rats treated with 60 μg ACTH/d had a higher amount of nucleosomes in the blood compared with rats treated with 10 μg ACTH/d, trilostane, or saline. We conclude that in healthy rats ACTH, but not trilostane, causes adrenal degeneration in a dose-dependent manner. Results of this study support the hypothesis that adrenal gland lesions seen in trilostane-treated dogs are caused by ACTH and not by trilostane.     

Mortality of centrarchid fishes in the Potomac drainage: survey results and overview of potential contributing factors

Skin lesions and spring mortality events of smallmouth bass Micropterus dolomieu and selected other species were first noted in the South Branch of the Potomac River in 2002. Since that year morbidity and mortality have also been observed in the Shenandoah and Monocacy rivers. Despite much research, no single pathogen, parasite, or chemical cause for the lesions and mortality has been identified. Numerous parasites, most commonly trematode metacercariae and myxozoans; the bacterial pathogens Aeromonas hydrophila, Aeromonas salmonicida, and Flavobacterium columnare; and largemouth bass virus have all been observed. None have been consistently isolated or observed at all sites, however, nor has any consistent microscopic pathology of the lesions been observed. A variety of histological changes associated with exposure to environmental contaminants or stressors, including intersex (testicular oocytes), high numbers of macrophage aggregates, oxidative damage, gill lesions, and epidermal papillomas, were observed. The findings indicate that selected sensitive species may be stressed by multiple factors and constantly close to the threshold between a sustainable (healthy) and nonsustainable (unhealthy) condition. Fish health is often used as an indicator of aquatic ecosystem health, and these findings raise concerns about environmental degradation within the Potomac River drainage. Unfortunately, while much information has been gained from the studies conducted to date, due to the multiple state jurisdictions involved, competing interests, and other issues, there has been no coordinated approach to identifying and mitigating the stressors. This synthesis emphasizes the need for multiyear, interdisciplinary, integrative research to identify the underlying stressors and possible management actions to enhance ecosystem health.     

Field study on colloid transport using fluorescent microspheres

Understanding colloid movement through the vadose zone is important, because colloids may facilitate transport of some less mobile contaminants. Experimental evidence of colloid transport in the vadose zone, especially at the field scale, is rare. We developed and tested a method to detect and quantify local concentrations of fluorescent microspheres (MS) with a diameter of 1 μm in unsaturated soil based on fluorescent microscopy. The detection limit was 400 × 10⁶ MS kg^?1 field‐moist soil for an automated counting method, and 20 × 10³ MS kg^?1 for manual counting. To test the method in the field, we applied a 40‐mm pulse with an input concentration of 14.6 × 10⁹ MS litre^?1 on two plots during 6 hours, together with bromide (Br^?) and the food dye Brilliant Blue (BB). The concentrations of MS were determined on horizontal cross‐sections by a randomly distributed sampling scheme, either directly after application or 90 days after application and a rainfall of 100 mm. Mass recoveries for the MS of 85 and 65% were acceptable in view of the field conditions. Even after infiltration of particle‐free water, the largest MS concentrations were measured at the soil’s surface, which pointed at physical retention mechanisms. An additional selective sampling of hydrologically active preferential flow pathways, guided by the dye infiltration patterns, revealed that the MS were transported to similar depths as BB, that is 0.80 m directly after irrigation and 1.7 m after 90 days. This implies that also a small fraction of the particulate tracers was rapidly transported to larger depths, regardless of their physico‐chemical properties.     

Monoclonal antibodies directed towards the two major cell populations in the bursa of Fabricius of the chicken

Two mouse monoclonal IgM antibodies, B.1 and B.2, have been produced using the mouse myeloma cell line Sp2/0-Ag 14 and spleen cells from mice immunized with chicken bursa cells. The binding of the monoclonal antibodies to cells in suspension or tissue sections was demonstrated by means of the unlabeled peroxidase-antiperoxidase method. B.1 recognizes 61% of the bursa cells, 10-14% of the cells of spleen and of the peripheral mononuclear blood leukocytes and 1% of the thymus cells. The B.1+ cells are regarded as B cells. Their location in tissue sections corresponds with the known B-dependent areas of lymphoid organs. Competitive binding and double marker experiments proved that the B.1 antigen is distinct from surface immunoglobulin (Ig). In the bursa all B.1+ cells are also Ig+, whereas in the thymus, spleen and blood only about 90% of the B.1+ cells show this conformity. B.2 mainly recognizes so called reticular epithelial and reticular cells of the bursa (36%), thymus (20%) and spleen (13%). The B.2+ cells represent the second major cell population of the bursa.     

In vitro effects of cisapride, metoclopramide and bethanechol on smooth muscle preparations from abomasal antrum and duodenum of dairy cows

The objective of this study was to investigate the effects of cisapride (CIS), metoclopramide (MET) and bethanechol (BET) on contractility parameters from smooth muscle preparations of the abomasal antrum and proximal duodenum of cows. Smooth muscle preparations were harvested shortly post-mortem from 42 healthy dairy cows, and concentration-response curves were performed by cumulative application of the drugs. Cisapride and MET did not have any significant effect on the contractility parameters studied, while BET induced a significant, concentration-dependent increase in basal tone (BT), mean amplitude (Amean), and area under the curve (AUC) in smooth muscle preparations from the abomasal antrum, but not from the duodenum. The effect of BET on BT was more pronounced in specimens with longitudinal orientation while the maximal obtainable effect (Vm) in Amean was more pronounced in circular-oriented preparations. Atropine (1 x 10-5 m) significantly inhibited the effect of BET, whereas pre-incubation with hexamethonium or tetrodotoxin (TTX) had no effect, suggesting that the effect was mediated by cholinergic receptors on the smooth muscle. The results may be relevant to diseases or disorders associated with gastric emptying and gastric hypomotility. Further investigations are warranted to investigate the potential ability of BET to enhance abomasal emptying of adult dairy cows.