Promotion of the cycling of diet-enhancing nutrients by african grazers

Experiments in Serengeti National Park, Tanzania, provide direct evidence that large, free-ranging mammalian grazers accelerate nutrient cycling in a natural ecosystem in a way that enhances their own carrying capacity. Both nitrogen and sodium were at considerably higher plant-available levels in soils of highly grazed sites than in soils of nearby areas where animal density is sparse. Fencing that uncoupled grazers and soils indicated that the animals promote nitrogen availability on soils of inherently similar fertility and select sites of higher sodium availability as well as enhancing that availability.     

The Importance of Having Zinc During In Vitro Maturation of Cattle Cumulus–Oocyte Complex: Role of Cumulus Cells

The aim of this study was to investigate the influence of zinc (Zn) on the health of cumulus–oocyte complex (COC) during in vitro maturation (IVM). Experiments were designed to evaluate the effect of Zn added to IVM medium on: DNA integrity, apoptosis, cumulus expansion and superoxide dismutase (SOD) activity of cumulus cells (CC). Also, role of CC on Zn transport during IVM was evaluated on oocyte developmental capacity. DNA damage and early apoptosis were higher in CC matured with 0 μg/ml Zn compared with 0.7, 1.1 and 1.5 μg/ml Zn (p < 0.05). Cumulus expansion did not show differences in COC matured with or without Zn supplementation (p > 0.05). Superoxide dismutase activity was higher in COC matured with 1.5 μg/ml Zn than with 0 μg/ml Zn (p < 0.05). Cleavage and blastocyst rates were recorded after IVM in three maturation systems: intact COCs, denuded oocytes with cumulus cells monolayer (DO + CC) and denuded oocytes (DO). Cleavage rates were similar when COC, DO + CC or DO were matured with 1.5 μg/ml Zn compared with control group (p > 0.05). Blastocyst rates were significantly higher in COC than in DO + CC and DO with the addition of 1.5 μg/ml Zn during IVM (p < 0.01). Blastocyst quality was enhanced in COC and DO + CC compared with DO when Zn was added to IVM medium (p < 0.001). The results of this study indicate that Zn supplementation to IVM medium (i) decreased DNA damage and apoptosis in CC; (ii) increased SOD activity in CC; (iii) did not modify cumulus expansion and cleavage rates after in vitro fertilization; (iv) improved subsequent embryo development up to blastocyst stage; and (v) enhanced blastocyst quality when CC were present either in intact COC or in coculture during IVM.     

Author Index to Volume 4 (2001)

Authors Index

Author Index to Volume 4 (2001)     

Physical Properties of Composted Materials Mixed with Sand

? The end product from the Portage, Wisconsin cocomposting facility is a loose, dark brown, organic material containing small fragments of glass, rubber, metal, plastics, and other materials that are resistant to decomposition. A research program was completed to determine the suitability of the compost for use in highway embankments or other engineered fills. Standard Proctor tests were conducted to determine the maximum density and optimum water content of the compost-sand mixtures. Direct shear tests were conducted on specimens compacted at maximum density and optimum water content. The cocomposted material mixed with sand proved to have sufficient shear strength for use in embankment construction.     

Large-scale molecular dynamics simulations of dislocation intersection in copper

The results of massively parallel three-dimensional molecular dynamics simulations of the perpendicular intersection of extended dislocations in copper are reported. The intersection process, which involves three of the four possible 111 glide planes in the face-centered cubic lattice, begins with junction formation, followed by unzipping, partial dislocation bowing, cutting, and, finally, unit jog formation. The investigation provides insights into this complex atomistic process, which is currently not accessible to experimental investigation.     

Assessment of organoleptic postmortem inspection techniques for bovine offal

Objective To evaluate organoleptic postmortem inspection techniques for bovine livers and kidneys.
Study design At Australian export abattoirs, bovine liver and kidneys are assessed and graded by qualified meat inspectors during normal operations. Over a 12-month period at a large abattoir in eastern Australia during 1997 and 1998, a sample of these organs was reassessed independently using a range of pathological and microbiological methods. Agreement between routine inspection and independent assessment was evaluated using methods of inter-rater agreement.
Results A total of 944 livers and 1374 kidneys were included in the study. All of these organs had been classified during routine inspection. The authors examined 363 livers and 329 kidneys both grossly and histologically, including 36 livers and 14 kidneys that were also subjected to microbiological examination. All other organs were only examined grossly. There was only a moderate level of agreement between the routine and independent assessment methods. For livers, the percentage agreement was 80.2%, McNemar's test of symmetry 55.2 (3 degrees of freedom, P < 0.001) and kappa 0.63. For kidneys, the percentage agreement was 67.8%, McNemar's test of symmetry 9.9 (1df, P = 0.002) and kappa 0.35.
Conclusions The results reinforce concerns from a number of authors about organoleptic postmortem inspection. Risk assessment methodologies offer the opportunity to modify inspection techniques in a manner that is most relevant to current public health concerns.     

Isolation of swine infertility and respiratory syndrome virus (isolate ATCC VR-2332) in North America and experimental reproduction of the disease in gnotobiotic pigs.

A recent epizootic of swine infertility and respiratory syndrome (SIRS) in a Minnesota swine herd was investigated. Examination of a sow, neonatal piglets, and stillborn fetuses obtained during the epizootic from the affected herd revealed interstitial pneumonitis, lymphomononuclear encephalitis, and lymphomononuclear myocarditis in the piglets and focal vasculitis in the brain of the sow. Fetuses did not have microscopic lesions. No cause for the infertility and respiratory syndrome was determined. Therefore, attempts were made to experimentally reproduce the disease. Eleven 3-day-old gnotobiotic piglets exposed intranasally to tissue homogenates of piglets from the epizootic became inappetent and febrile by 2-4 days postexposure and had interstitial pneumonitis and encephalitis similar to that seen in the field outbreak. After 2 blind passages in gnotobiotic piglets, tissue homogenates were cultured on continuous cell line CL2621, and a cytopathic virus (ATCC VR-2332), provisionally named SIRS virus, was isolated. Gnotobiotic piglets exposed intranasally to the SIRS virus developed clinical signs and microscopic lesions that were the same as those in piglets exposed to the tissue homogenates, and the virus was reisolated from their lungs. This is the first isolate of SIRS virus in the United States that fulfills Koch's postulates in producing the respiratory form of the disease in gnotobiotic piglets and the first report of isolation and propagation of the virus on a continuous cell line (CL2621). The virus is designated as American Type Culture Collection VR-2332.     

Histopathologic and immunocytochemical studies of distemper in harbor porpoises

During 1988 thousands of harbor seals (Phoca vitulina) died in European seas as a result of morbillivirus infection. Six harbor porpoises (Phocoena phocoena) found stranded on the coast of Northern Ireland in late 1988 were submitted to our laboratory for necropsy. Pneumonia was the main necropsy finding in three of these animals. Microscopic lung lesions characterized by necrosis of bronchial and bronchiolar epithelium and infiltration of alveoli with leukocytes, lymphoid cells, macrophages, and multinucleate syncytia were seen in all six porpoises. Cytoplasmic and nuclear acidophilic inclusions characteristic of morbillivirus infection were common in bronchial and bronchiolar epithelial cells and in alveolar macrophages and syncytia. Brain alterations included degeneration and necrosis of neurons, microglial infiltration, and perivascular cuffing. There were cytoplasmic and nuclear acidophilic inclusions in many neurons. Immunoperoxidase staining of morbillivirus antigen was seen in many tissues including lung, brain, spleen, and urinary bladder. Alterations in our porpoises were similar to those seen in distemper in seals and many species of terrestrial mammals. Systemic viral disease has not previously been documented in Cetacea.