ALTERNATIVES TO ANTIBIOTIC USE: PROBIOTICS FOR THE GUT

Developed countries are not immune from serious food-borne diseases, and the source is often the intestine of cattle, sheep and poultry livestock. Outbreaks of Escherichia coli 0157, most recently killing people in Ontario, and of salmonella and shigella food poisoning especially during summer months, remind us of the seriousness of the problem. Thus, there is renewed interest in alternative approaches to antibiotics to control bacterial diseases, both in humans and veterinary medicine.3-4 Whatley, B. T. 1987. “A ‘Natural’ Answer to Antibiotics.”. In InBooker T. Whatley's Handbook on How to Make $100,000 Farming 25 Acres: With Special Plans for Prospering on 10 to 200 Acres Edited by: DeVault, G. 137–139. Cramer, C. 1990. Healthy Livestock with Fewer Drugs. The New Farm, 12: 23–30.   Consumers are believed to be concerned not only about bacterial pathogens being in meat, but also that residues of antibiotics may also be present. The trend to “natural” farming without exposure to chemicals, pesticides and herbicides could be one reason for increased interest in probiotics for livestock farming.     

CARBON DIOXIDE AS A FACILITATING AGENT IN THE INITIATION AND GROWTH OF BUBBLES IN ANIMALS DECOMPRESSED TO SIMULATED ALTITUDES

1. Rats killed in a variety of ways (broken neck, nembutal, anoxia, electrocution) may undergo extensive bubble formation when subsequently decompressed from atmospheric pressure to simulated altitudes of 50,000 feet. On autopsy at sea level, large numbers of bubbles are found throughout the vascular system in the majority of animals. These bubbles appear to originate in small vessels deep within muscular regions, later spreading widely in arterial and venous systems. Dead rabbits and frogs also bubble profusely on decompression. 2. Bubble formation in dead animals is attributed primarily to the accumulation of CO₂, derived from residual cellular respiration after death, and from anaerobic glycolysis with attendant decomposition of bicarbonates in blood and tissue fluids. If anaerobic glycolysis is inhibited by using sodium iodoacetate as a lethal agent, bubble formation is greatly reduced or lacking on subsequent decompression. 3. Experiments in vitro suggest that high concentrations of CO₂ favor bubble formation by reducing the degree of mechanical disturbance necessary. 4. Administration of CO₂ in high concentrations to living frogs lowers the minimum altitude (pressure equivalent) at which bubble formation occurs, with exercise, in untreated animals. Pre-treatment with CO₂ also reduces the degree of muscular activity necessary for bubbles to form in frogs at higher altitudes. 5. Analyses have been made of the gas content of bubbles taken directly from the large veins of decompressed frogs and rats. In living animals the figures obtained indicate rapid equilibration with gas tensions in the blood. Bubbles taken from decompressed dead rats may contain 60–80 per cent CO₂. 6. The bearing of these experiments on the mechanisms of bubble initiation and growth in normal living animals is discussed. Reasons are given for suggesting that CO₂, due largely to its high dissolved concentration in localized active regions, may be an outstanding factor in the initiation and early growth of bubbles which in later stages are expanded and maintained principally by nitrogen.     

霉菌性阴道炎与抗菌素使用关系的病例对照研究

本文对霉菌性阴道炎与抗菌素使用及其它因素的关系进行了分析。病例对照研究结果表明,抗菌素使用与霉菌性阴道炎发病的联系极其明显（ＯＲ＝４２．５７）。应用一种以上抗菌素能显著增加患病危险（ＯＲ＝４２８．８３）。如果使用抗菌素时间不超过一周,患病危险性虽有增加,但未达显著水平,但超过一周使相对危险度达３１１．０。未发现自身和丈夫手足霉菌感染、公共浴池洗澡、避孕措施等与该病有关,但年龄和职业（干部）具有增加发病危险的意义。     

利用大肠杆菌质粒检测与分离痘苗病毒的启动子

本文发现,痘苗病毒DNA一些巳知的启动子序列和一些功能尚不清楚的DNA片段,可以在大肠杆菌中起始氯霉素乙酰基转移酶(Chloramphenicol Acetyltrsnsferase,简称CAT)基因的转录和表达,使转化细菌呈现氯霉素抗性表型,这一结果证明,痘苗病毒的启动子可以被大肠杆菌的RNA多聚酶所识别并有效工作。同时发现不同启动子具有不同的强度,利用大肠杆菌质粒分离和检测痘苗病毒的启动子序列,不仅可以研究痘苗病毒基因组的表达调节特点,而且也为组建痘苗病毒表达载体提供了一个快速、简便可靠的方法。