Effect of Hypercapnia or Xylazine on Lateral Ventricle and Lumbosacral Cerebrospinal Fluid Pressures in Pentobarbital-anesthetized Horses

Facial artery pressure, central venous pressure, heart rate, and lateral ventricle cerebrospinal fluid (CSF) pressure (LV-CSFP) were measured in 10 pentobarbital-anesthetized horses at arterial partial pressure of carbon dioxide (PaCO₂) values of 40,60, and 80 mm Hg, produced by varying the inspired carbon dioxide concentration. Variables were recorded at 5-minute intervals for 15 minutes at each level of PaCO₂. Arterial blood gas analysis was performed at the end of the 15-minute time period for each level of PaCO₂. Lateral ventricle CSF pressure was significantly increased (p < .05) at a PaCO₂ of 80 mm Hg. Cardiovascular variables were not significantly changed by changing PaCO₂. The PaCO₂ was returned to 40 mm Hg; 1.1 mg xylazine/kg body weight was injected intravenously in eight horses, and data were collected for 60 minutes. No significant changes were observed. No changes were observed in two control horses not receiving xylazine. Subsequently, placement of a lumbosacral subarachnoid catheter allowed simultaneous measurement of LV-CSFP and lumbosacral CSF pressure (LS-CSFP) at PaCO₂ values of 40,60, and 80 mm Hg. The Pearson Correlation Coefficient between LV-CSFP and LS-CSFP was 0.94 (p < .0001) It was concluded that changes in CSF pressure could be detected at the lateral ventricle and the lumbosacral space; increasing PaCO₂ to 80 mm Hg resulted in significant increases in LV-CSFP; xylazine does not increase LV-CSFP in pentobarbital-anesthetized, normocapnic horses; and under the conditions of this experiment, LV-CSFP and LS-CSFP were closely correlated.     

The influence of temperature and water table position on carbon dioxide and methane emissions from laboratory columns of peatland soils

Laboratory columns (80 cm long, 10 cm diameter) of peat were constructed from samples collected from a subarctic fen, a temperate bog and a temperate swamp. Temperature and water table position were manipulated to establish their influence on emissions of CO₂ and CH₄ from the columns. A factorial design experiment revealed significant (P < 0.05) differences in emission of these gases related to peat type, temperature and water table position, as well as an interaction between temperature and water table. Emissions of CO₂ and CH₄ at 23°C were an average of 2.4 and 6.6 times larger, respectively, than those at 10°C. Compared to emissions when the columns were saturated, water table at a depth of 40 cm increased CO₂ fluxes by an average of 4.3 times and decreased CH₄ emissions by an average of 5.0 times. There were significant temporal variations in gas emissions during the 6-week experiment, presumably related to variations in microbial populations and substrate availability. Using columns with static water table depths of 0, 10, 20, 40 and 60 cm, CO₂ emissions showed a positive, linear relation with depth, whereas CH₄ emissions revealed a negative, logarithmic relation with depth. Lowering and then raising the water table from the peat surface to a depth of 50 cm revealed weak evidence of hysteresis in CO₂ emissions between the falling and rising water table limbs. Hysteresis (falling > rising limb) was very pronounced for CH₄ emissions, attributed to a release of CH₄ stored in porewater and a lag in the development of anaerobic conditions and methanogenesis on the rising limb. Decreases in atmospheric pressure were correlated with abnormally large emissions of CO₂ and CH₄ on the falling limb. Peat slurries incubated in flasks revealed few differences between the three peat types in the rates of CO₂ production under aerobic and anaerobic conditions. There were, however, major differences between peat types in the rates of CH₄ consumption under aerobic incubation conditions and CH₄ production under anaerobic conditions (bog > fen > swamp), which explain the differences in response of the peat types in the column experiment.     

MALATE DEHYDROGENASE: MULTIPLE FORMS IN SEPARATED BLASTOMERES OF SEA URCHIN EMBRYOS

Sea urchin embryos at the 64-cell stage were dissociated by treatment with trypsin and separated by centrifugation on a sucrose gradient. The large blastomeres have two and the small blastomeres have three bands of L-malate dehydrogenase activity, which are separated by disk microelectrophoresis on polyacrylamide gel, whereas unfertilized eggs have five.     

The distribution of opaline silica bodies in the leaf sheaths of two perennial ryegrass cultivars differing in their susceptibility to attack by dipterous stem-borers

Leaf sheaths of two cultivars of perennial ryegrass were prepared by chemical oxidation so that the silica bodies in the tissues could be studied. The cultivar Fortis, which is relatively resistant to stem-borer attack, contained many-intercostal silica bodies in the leaf sheath but the more susceptible cultivar S24 contained few. If the pattern of silica bodies affects levels of stem-borer infestation, it may be possible to breed for this characteristic.     

Cranial cruciate ligament rupture in the dog—a retrospective study comparing surgical techniques

SUMMARY Three surgical techniques, grouped as intra-articular techniques, extra-capsular techniques and fibular head transposition, were used for repair of the cranial cruciate ligament (CCL)-deficient stifle in 113 dogs over a 4 year 4 month period. The clinical outcome of the techniques were compared using information provided by the owners and physical examination. Regardless of surgical technique, 85.7 to 91.0% of dogs showed clinical improvement after surgery. However, less than 50% of dogs became clinically sound on the operated leg and 9.0 to 14.3% of dogs remained persistently lame on the operated leg. No statistical association was found between result after surgery and age, body weight, sex, duration of injury before surgery, association with injury, tibial plateau angle, degree of radiographic osteoarthritis before surgery or the presence of concurrent medial meniscal injury. On physical examination, extra-capsular techniques appeared superior to the fibular head transposition in terms of joint stability and limb function. Concurrent medial meniscal injury necessitating meniscectomy existed in 48.0% of cases. Twenty-two percent of dogs ruptured their contralateral CCL at an average of 14 months after the first.     

花蛤高效生态养殖池中浮游动物生态特征研究

于2007年11月-2008年3月,研究莆田花蛤生态养殖池浮游动物的种类组成和数量分布特征,并探讨了其与环境因子的关系。结果表明,在藻类池及花蛤养殖池中所采集的样品,浮游动物有34种,其中原生动物25种,占74％,桡足类5种,占15％,端足类1种,占2．9％,其它浮游动物3种,占8．8％,原生动物占比例最多。卡拉拟铃虫,丁丁急游虫、浮游幼虫和强额拟哲水蚤是主要优势种。不同月份浮游植物数量变化直接影响着浮游动物的数量,浮游动物的数量受海水温度、溶氧影响不大,不同月份浮游动物的分布存在差异。