Dihydroorotic acid dehydrogenase: introduction into erythrocyte by the malaria parasite

Mature, circulating mammalian erythrocytes lack dihydroorotic acid dehydrogenase activity. However, we have detected activity, which appears to reside in an enzyme, in malaria parasites purified from mammalian blood.     

基于PhotoScan的径流小区三维重建参数优化

提高径流小区数字地面模型精度是应用三维重建技术研究面蚀细沟间与细沟侵蚀过程的关键。以位于黑龙江省海伦市的中国科学院海伦水土保持监测研究站的裸地小区为研究对象,以验证点与控制点误差比和数字高程模型（Digital elevation model,DEM）误差为指标,优化Agisoft PhotoScan三维重建径流小区的处理参数,降低DEM误差。PhotoScan的精度参数和相机模型设置对DEM误差有较大影响。优化后的验证点与控制点误差比降低35%,改善了径流小区DEM对地面控制点的过度拟合。优化后的相机模型包含焦距、像主点、径向畸变、切向畸变等。基于单点和点云的验证结果表明,优化过程误差降低约40%。相对于默认参数设置下的验证点误差（20.0mm）,优化后的验证点误差为11.0mm,与细沟侵蚀深度标准相当（沟深大于等于10mm）,因此优化后的径流小区三维重建过程更适宜于细沟侵蚀过程的三维表达。     

Inorganic and organic sulfur cycling in salt-marsh pore waters

Sulfur species in pore waters of the Great Marsh, Delaware, were analyzed seasonally by polarographic methods. The species determined (and their concentrations in micromoles per liter) included inorganic sulfides (相似文献   

The weakest link: medroxyprogesterone acetate in pig feed

Medroxyprogesterone acetate (MPA)-contaminated feed arrested the onset of farrowing, and induced post-lactational anoestrus in sows. Sixty percent of the sows developed cystic ovaries after weaning following exposure to pharmaceutical waste of MPA in glucose syrup. This waste ended up in acidified feed of by-products of a sow farm, and proved to be the cause of the disorders. Analysis by thin layer chromatography and Gas Chromatography/Mass Spectrometry of renal fat from 10 slaughter sows demonstrated residues of 2.5-8 ppb of MPA. Within the European Union use of MPA is illegal as growth promoter in production animals, and therefore MPA-exposed farms were placed under official control by the general inspection service. Clinical signs and diagnostic procedures of the initial case are presented and the role of the veterinary practitioner in detecting potential food safety hazards is discussed.     

The effects of exogenous xylanase supplementation on the in vivo generation of xylooligosaccharides and monosaccharides in broilers fed a wheat-based diet

ABSTRACT

1. This study quantified xylanase-induced changes in soluble monosaccharides, xylooligosaccharides (XOS) and volatile fatty acid (VFA) contents of the different sections of the gastrointestinal tract (GIT) and whether these were related to altered bird performance.

2. An in vitro digestion of the wheat-based diet was carried out with the xylanase (Econase XT at 16,000BXU/kg diet) to compare the in vitro and in vivo generation of these XOS and monosaccharides. For the in vivo study, 80 male Ross 508 b roiler chicks were split into two groups fed a wheat-based diet with or without Econase XT (16,000BXU/kg diet) for 21 days.

3. There were no effects of Econase XT inclusion on growth performance characteristics, likely a result of the high-quality wheat diet, the corresponding high performance of the control group (FCR average of 1.45 in controls) and the relatively young age of the birds (from four to 26 days of age).

4. Econase XT supplementation increased the xylotetraose (X₄) content in the colon (P = 0.046, enzyme x GIT section interaction) and the xylose contents in the colon and caeca (P < 0.001, enzyme x GIT section interaction).

5. The trend for increased acetate production in the caeca of Econase XT treated birds (P = 0.062) suggested that the XOS generated were subsequently fermented in the caeca, potentially impacting upon the types of microbiota present.

6. The present study suggested that wheat arabinoxylan degradation was enhanced by xylanase supplementation, which may have increased the production of beneficial volatile fatty acids (VFA) in the caeca, and thereby potentially modulated the caecal microbiome, but without affecting bird performance at this early age.     

Ocular metastasis of a vaccine-associated fibrosarcoma in a cat

A 6‐year‐old, neutered male domestic shorthair cat was evaluated for a recurrent vaccine‐associated fibrosarcoma. The cat had three excisions of the tumour prior to presentation and was referred for radiation therapy. Ten months following treatment with radiation therapy, the cat was presented again for a cloudy appearance to the eye. An exenteration was performed, and biopsy revealed fibrosarcoma. At the same time, two discrete pulmonary nodules were identified on thoracic radiographs. Two doses of doxorubicin (20 mg/m²) and cyclophosphamide (100 mg/m²) were administered intravenously 3 weeks apart. Despite treatment, the pulmonary nodule doubled in size. This case represents the first antemortem report of ocular metastasis of a vaccine‐associated sarcoma and supports the highly aggressive nature of these tumours.     

The use of intrathecal analgesia and contrast radiography as preoperative diagnostic methods for digital flexor tendon sheath pathology

Reasons for performing study: The sensitivity of ultrasonography for the diagnosis of manica flexoria (MF) tears within the digital flexor tendon sheath (DFTS) is lower than for diagnosis of marginal tears of the deep digital flexor tendon (DDFT). Additional diagnostic tools would assist in appropriate decision making for either conservative or surgical management. Objectives: To evaluate the improvement in lameness of horses with MF or DDFT tears following intrathecal analgesia and to assess the sensitivity and specificity of contrast radiography for the diagnosis of these tears. Methods: The case records of horses presented to a referral clinic over a 7‐year period that underwent intrathecal diagnostic analgesia, or intrathecal analgesia and contrast radiography, of the DFTS with subsequent tenoscopy were examined. Results: Fifty‐three limbs had intrathecal diagnostic analgesia performed and 23 contrast tenograms were assessed in horses undergoing DFTS tenoscopy. Horses with DDFT tears were significantly more likely to respond positively to intrathecal diagnostic analgesia than those with MF tears (P = 0.02). Using contrast radiography, tears of the MF were predicted with an overall sensitivity of 96% and specificity of 80%; marginal tears of the DDFT were predicted with an overall sensitivity of 57% and specificity of 84%. Conclusions: The results of intrathecal analgesia of the DFTS in combination with contrast radiography have a high sensitivity for predicting MF tears. The sensitivity of contrast radiography for predicting tears of the DDFT is lower but the specificity remains high. Potential relevance: Contrast radiography performed at the same time as intrathecal analgesia provides useful information regarding the presence of MF tears and DDFT tears, which can assist in the decision of whether to manage the lameness conservatively or with tenoscopic evaluation.     

Shoot biomass growth is related to the vertical leaf nitrogen gradient in Salix canopies

Plant canopy optimization models predict that leaf nitrogen (N) distribution in the canopy will parallel the vertical light gradient, and numerous studies with many species have confirmed this prediction. Further, it is predicted that for a given canopy leaf area, a low vertical light extinction coefficient will promote rapid growth. Therefore, the ideal canopy of fast-growing plants should combine high leaf area index with a low light extinction coefficient; the latter being reflected in a flat vertical leaf N gradient throughout the canopy. Based on data from an experimental Salix stand (six varieties) grown on agricultural land in central Sweden, we tested the hypothesis that shoot growth is correlated with vertical leaf N gradient in canopies of hybrid willows bred for biomass production, which could have implications for Salix breeding. Tree improvement research requires screening of growth-related traits in large numbers of plants, but assessment of canopy leaf N gradients by chemical analysis is expensive, time-consuming and destructive. An alternative to analytical methods is to estimate leaf N gradients nondestructively with an optical chlorophyll meter (SPAD method). Here we provide a specific calibration for interpreting SPAD data measured in hybrid willows grown in biomass plantations on fertile agricultural land. Based on SPAD measurements, a significant and inverse relationship (r(2) = 0.88) was found between shoot biomass growth and vertical leaf N gradient across canopies of six Salix varieties.     

Aberrant extradural spinal migration of Spirocerca lupi: four dogs

Spirocerca lupi is a nematode mainly affecting dogs but has been found in other animals, particularly carnivores. Anatomical areas of typical and aberrant migration vary. This report describes four cases of Spirocerca lupi causing neurological symptoms, similar to thoracolumbar disc syndrome, as a result of aberrant migration of the nematode into the spinal canal. In two of the cases, the nematode could be demonstrated intraoperatively. The third was discovered on post-mortem examination, while the fourth case displayed compelling evidence of Spirocerca lupi involvement. Surgical removal of the Spirocerca lupi nematode would be the treatment of choice in cases of spinal migration, with therapeutic and preventive treatment with doramectin instituted to treat remote sites and prevent re-infection. In areas endemic for spirocercosis, Spirocerca lupi should be considered as an important differential diagnosis in cases that are presented with clinical signs suggestive of a spinal cord lesion.     

Exocrine pancreatic secretion in pigs fed sow's milk and milk replacer, and its relationship to growth performance

The objective of this study was to quantify and compare the effects of sow's milk and 2 milk replacer diets (containing clotting or non-clotting protein sources) on exocrine pancreatic secretion, plasma cholecystokinin, and immunoreactive cationic trypsin in pigs. In addition, the relationship between exocrine pancreatic secretion and growth in milk-fed pigs was studied. In a changeover experiment, 9 chronically catheterized pigs of 6.6 +/- 0.19 kg of BW were studied for 3 wk. Pigs were assigned to each of 3 diets. Exocrine pancreatic secretion was measured from the third to the seventh day on each diet. The protein content and trypsin activity of the pancreatic juice were measured. Blood samples were taken at 10 min before and after milk ingestion and were analyzed for cholecystokinin and immunoreactive cationic trypsin. Pancreatic protein and trypsin secretion did not differ between pigs fed sow's milk and those fed milk replacer, but the volume secreted was less for the pigs fed sow's milk (0.75 vs. 1.03 mL x kg(-1) x h(-1); P < 0.01). A postprandial response to milk intake was not observed. The 2 milk replacer diets did not affect exocrine pancreatic secretion differently. The average exocrine pancreatic secretion (volume, 0.94 mL x kg(-1) x h(-1); protein, 4.28 mg x kg(-1) x h(-1); trypsin, 1.65 U x kg(-1) x h(-1)) was intermediate between literature values for suckling and weaned pigs. Plasma cholecystokinin was elevated (approximately 18 pmol x L(-1)) and showed low correlations with the pancreatic secretion traits. Plasma immunoreactive cationic trypsin was not significantly related to any of the pancreatic secretion traits and should therefore not be used as an indicator for exocrine pancreatic function in milk-fed pigs. Exocrine pancreatic secretion varied substantially among individual pigs (protein, 0.22 to 13.98 mg x kg(-1) x h(-1)). Pancreatic protein and trypsin secretion showed a positive, nonlinear relationship with performance traits. It was concluded that neither specific sow's milk ingredients nor the protein source are responsible for a low pancreatic protein secretion in suckling pigs. Exocrine pancreatic secretion was positively correlated with ADG in pigs at an identical milk intake.