Fluctuating PEEP (F–PEEP) versus conventional PEEP in dogs with asymmetrical lung injury

Fluctuating PEEP (F-PEEP) is a newly developed PEEP in which end-expiratory pressure (EEP) is periodically changed within a certain range. In a dog model with unilateral lung injury induced by the introduction of hydrochloric acid, F-PEEP in which the EEP was periodically changed from 0.5 to 1.5 kPa at periods of 6 min, and conventional PEEP (C-PEEP) with an optimized EEP of 1.0 kPa, were each applied for 30 min. F-PEEP produced a significantly greater improvement of PaO2 and intrapulmonary shunt (QS/QT) than C-PEEP, and at the low EEP phase, the greatest improvement accompanied by an increased dynamic compliance and a large cardiac output was obtained. These results suggest that F-PEEP provides a useful mode of artificial ventilation for the treatment of unilateral lung injury.     

Tyramine-Induced cardiac arrhythmias

Five out of 12 physically healthy patients with depression undergoing a tyramine pressor test developed cardiac arrhythmias. These arrhythmias occurred in drug-free patients in three out of 12 infusions following as little as 0.03 mg/kg of tyramine and after moclobemide, a reversible inhibitor of monoamine oxidase-A, in four out of 14 tyramine infusions with as little as 0.04 mg/kg of tyramine. The arrhythmias seen were independent of patient's age and occurred both before and after 30 mmHg elevations in systolic blood pressure. Electrocardiographic abnormalities and arrhythmias seen were a loss of p waves, sinus tachycardia, frequent atrial ectopic beats, atrial premature beats, Wenckebach phenomenon, junctional rhythm, ventricular ectopics, varying QRS configurations, and ventricular bigeminy. Tyramine, both oral and intravenous, caused similar reproducible changes in dogs, though not in rats, mice or guinea pigs. Practical implications are that tyramine pressor testing in humans should be performed cautiously and only with adequate cardiac monitoring and resuscitation facilities at hand. These findings suggest that a normal dietary component can induce serious cardiac arrhythmias, and that a low-tyramine diet may be of value for patients who are susceptible to cardiac arrhythmias.     

Occurrence and Distribution of Bone Tumors in Beagle Dogs Exposed to 90Sr

Radiation-induced bone tumors in beagle dogs exposed to ⁹⁰Sr have been evaluated in terms of their incidence, time of appearance, occurrence as multiple tumors, anatomic distribution, and the influence of sex on their development. Among dogs fed ⁹⁰Sr during skeletal development, the incidence of bone tumors was dose dependent. Tumors thus appeared in 10 of 19 dogs receiving average skeletal doses of 130 Gy, 15 of 60 receiving 97 Gy, 5 of 61 receiving 61 Gy, 2 of 65 receiving 26 Gy, and 1 of 40 receiving 1.3 Gy. No tumors appeared among 66 dogs who received 8 Gy, 78 who received 0.3 Gy, and 80 non-irradiated controls, all of which have been observed for life. Among dogs given a single intravenous injection of ⁹⁰Sr in early adulthood, tumor production was somewhat higher than among ⁹⁰Sr-fed dogs at the same radiation dose: bone tumors were present in 6 of 25 dogs who received 62 Gy and 1 of 20 dogs who received 7.5 Gy. Bone tumors appeared sooner and were more often multiple in animals receiving the higher doses. Long bones were the sites of most of the tumors appearing after the highest dose level. Bones of the head, particularly the mandible, were the predominant site of tumors in the next highest dose level group.     

An experimental model for canine visceral leishmaniasis

Seven mixed-breed dogs were challenged with either promastigotes or amastigotes of Leishmania donovani infantum strains recently isolated from naturally infected dogs. Different routes and numbers of parasites were utilized and each dog was monitored for at least 1 year post-infection. Anti-parasite specific antibody levels were measured by enzyme-linked immunosorbence, immunofluorescence, crossed-immune electrophoresis and Western blotting on crude antigen. Western blotting on two pure parasite proteins, dp72 and gp70-2, was also done. Mitogenic and antigen-specific stimulation of peripheral blood lymphocytes was monitored; and the haematological, clinical and parasitological parameters measured. Dogs challenged with amastigotes exhibited a more pronounced humoral response to leishmanial antigens. Only in one case was strong antigen-specific proliferation detected. Clinical signs of disease, including hypergammaglobulinaemia, enlarged lymph nodes and the presence of parasites, were also more apparent in the dogs challenged with amastigotes. None of the seven dogs died. Serum antibodies to leishmanial antigens were apparent between 1.5 to 3 months following challenge and correlated with the appearance of enlarged lymph nodes, hypergammaglobulinaemia and the presence of parasites in tissue biopsies. Serum antibodies remained chronically high in these dogs throughout the period of the study. Only one dog (1/3) challenged intravenously with promastigotes and the dog challenged intradermally with amastigotes produced transient antibody responses to leishmanial antigen.     

降钙素基因相关肽对犬冠脉流量及冠状动脉的作用

本研究通过整体及离体灌流实验观察到重庆冠脉狭窄时，犬冠脉流量（ＣＢＦ），平均动脉压（ＭＡＰ）明显减小，而心率（ＨＲ）则增加。狭窄３０ｍｉｎ后由冠状动脉注射降钙素基因相关肽（ＣＧＲＰ）０．３μｇ／ｋｇ后，ＣＢＦ、ＭＡＰ和ＨＲ可恢复正常水平。同时，缺血犬的离体冠状动脉对ＣＧＲＰ的反应也出现改变。大冠脉舒张反应明显降低，而小冠脉的舒张反应与正常相比，无明显改变，这可能与缺血后大冠脉的内皮细胞容易损伤有关。同时也提示:急性心肌缺血时，冠脉流量的减少，主要由于小冠状动脉收缩所致。     

奇奥心血丹滴丸对麻醉犬血流动力学的作用

目的观察奇奥心血丹滴丸对麻醉犬血流动力学的作用.方法3%戊巴比妥钠静脉麻醉,颈总脉插管及左心室插管,测量血压、心率、心输出量、左室内压、左室舒张末压、±dp/dtmax等血流动力学指标.结果奇奥心血丹滴丸可明显降低血压、心率、心输出量、左室内压、±dp/dtmax.结论奇奥心血丹丸具有负性频率、负性肌力及降低血压等作用.     

高频喷射通气时麻醉犬动脉血二氧化碳分压的估计

作用测定５－８次常频呼吸后呼气末二氧化碳分压的方法，探讨了高频喷射通气时麻醉犬动脉脉血二氧化碳分压与Ｐｅｔｃｏ２的关系，结果表明，在通气频率分别为６０，１００及２００次／ｍｉｎ时，Ｐｅｔｃｏ２和Ｐａｃｏ２均无显性差异，Ｐｅｔｃｏ２呈显相关（ｒ＝０．８３，Ｐ＜０．０１）。结果提示，测定５－８次常频呼吸后的Ｐｅｔｃｏ２可较准确地评估ＨＦＪＶ时麻醉犬的Ｐａｃｏ２。