CHANGES IN ECHOCARDIOGRAPHIC VARIABLES OF LEFT VENTRICULAR SIZE AND FUNCTION IN A MODEL OF CANINE NORMOVOLEMIC ANEMIA

The objective of this study was to document changes in echocardiographic variables of left ventricular size and function noninvasively during acute normovolemic anemia. This model was developed as a pilot study with the purpose of providing baseline information to investigate the pathophysiology, and more specifically the effect on the heart, of canine babesiosis-induced anemia. The study group comprised of 11 mature healthy Beagle dogs that weighed between 9 and 15 kg. Severe normovolemic anemia was induced over a 3-4-day period by serial bleeding while maintaining normovolemia by autotransfusing plasma and infusing crystalloids. The dogs were then allowed to recover. Preanemic (mean Hct 46.7%, standard deviation [SD] 2.4%) echocardiographic variables of left ventricular performance (Fractional shortening, ejection fraction, end-systolic and end-diastolic ventricular volumes, cardiac index, and heart rate) were compared with those in the severely (mean Hct 15.3%, SD 1.1%), moderately (Hct mean 24.7%, SD 1.5%), and mildly (mean Hct 33.5%, SD 2.5%) anemic states, and between the anemic states. With the exception of end diastolic volume, there was a statistically significant (P < 0.05) increase in all variables in the severely anemic state vs. the preanemic and the mild and moderate anemic states. In concordance with previous invasive models, a hyperdynamic state of the left ventricle develops in response to experimentally induced acute canine normovolemic anemia in the conscious dog. Echocardiography has promise as a noninvasive technique of evaluating the cardiac changes in dogs having canine babesiosis.     

Xylazine-induced mydriasis in rats and its antagonism by α-adrenergic blocking agents

Pupillary response to xylazine (10-300 micrograms/kg, i.v.) norepinephrine (1-30 micrograms/kg. i.v.) and atropine (3-100 micrograms/kg, i.v.) were observed in rats anaesthetized with pentobarbital. Xylazine caused a dose-dependent mydriasis which was antagonized by a selective alpha 2-adrenergic blocking agent, yohimbine (2.5 mg/kg, i.v.). was less effective in antagonizing this effect of xylazine. A selective alpha 1-adrenergic blocking agent, prazosin (2.5 mg/kg, i.v.) was ineffective in reducing the xylazine-induced mydriasis. In contrast, both phentolamine and prazosin blocked the pupillary dilation produced by norepinephrine, while yohimbine was much less effective in antagonizing norepinephrine-induced mydriasis. Atropine also induced a dose-dependent mydriasis which was not affected by yohimbine pretreatment. The present study suggests that the mydriatic effect of xylazine in the rat is mediated by an adrenergic mechanism, possibly by stimulating the alpha 2-adrenergic receptors in the iris and CNS.     

大元麦条纹病(Helminthosporium gramineum Rubh.)防治研究的初步报告

 江苏省大元麦种植面积约一千余万亩,尤以南通、扬州、监城、镇江四个专区为多。条纹病历年严重,因此防治条纹病以保证增产,实属刻不容缓。     

NASAL SALT EXCRETION AND THE POSSIBLE FUNCTION OF THE CLOACA IN WATER CONSERVATION

Secretion of concentrated salt solutions from the nasal region was observed in several terrestrial birds and reptiles. In the secreted fluid potassium usually exceeded sodium concentrations, with chloride and bicarbonate as the major anions. It is suggested that the extrarenal excretion of salts is related to the reabsorption of water in the cloaca, that it is necessary for the production of urine with a particularly low water content, and perhaps was prerequisite for the evolution of efficient cloacal water conservation.