Mouse scrapie and polyadenylated RNA metabolism in L cells

It has previously been reported that infection of mice with the scrapie agent alters polyadenylated RNA (poly (A) RNA) metabolism. In particular, it was claimed that incubation of L cells with extracts from scrapie-infected mice changed the level of poly (A) RNA in the L cells. We have attempted to repeat this work, using the original techniques, but have been unable to confirm the published findings. Furthermore our work suggests that the techniques used would not have yielded purified poly (A) RNA, and analysis of the data from the previous publications supports this view.     

Reversed phase HPLC analysis of α- and β-carotene from selected raw and cooked vegetables

Traditional AOAC colorimetric procedures for carotenoid analysis are known to lack specificity and accuracy. Newer HPLC methods provide the investigator with a more precise tool for carotenoid quantification in foods and tissues. In the present studies, reverse phase HPLC was utilized to evaluate the - and -carotene content in raw and cooked leaves of lettuce, spinach and winged bean as well as in the carrot root. The vegetables were boiled or steamed and the true retention of - and -carotene in the cooked products was determined. Boiling for 30 minutes resulted in a 53 and 40% loss of -carotene from lettuce and carrots, respectively. Full retention or even an increase in -carotene content in boiled winged bean leaves and spinach was noted. Steaming resulted in very good retention of - and - carotene in all vegetables (83–139% retention). Thus, although cooking procedures (especially boiling) may result in oxidative loss of carotenoids in some vegetables, heat treatment increases the chemical extractability of - and -carotene in others. The presence of carotenoproteins in some vegetables may effect the heat stability of extractability of - and - carotene.     

Characterization of portal lymphocytic infiltrates in feline liver

To better understand the relationship of portal lymphocytic infiltrates to feline inflammatory liver disease, liver sections were semiquantitatively evaluated from healthy cat and liver sections randomly selected at necropsy from clinical cases. Healthy specific pathogen-free kittens and healthy young adult cats had up to 10 lymphocytes and plasma cells per portal area. Neutrophils were infrequently seen in portal areas. Approximately one-third of sections obtained from clinical cases younger than 10 years had increased numbers of lymphocytes and plasma cells in portal areas. Seventy percent of these had a concurrent increase in neutrophils. Eighty-two percent of liver sections obtained from clinical cases older than 10 years had increased numbers of portal lymphocytes and plasma cells. Almost all of these sections had concurrent fibrosis and bile duct proliferation. These data indicate that a progressive lymphocytic portal hepatitis is a common finding in cats older than 10 years.     

Anti-A isoagglutinins in two blood type B cats are IgG and IgM

Sera from two blood type B cats had strong isoagglutinating and isohemolyzing titers against blood type A erythrocytes. In order to determine the class of the immunoglobulins, sera from the cats were pooled, ammonium sulfate precipitated, and gel filtered using sepharose 6B to separate the immunoglobulins by molecular size. The immunoglobulin concentrate separated into two fractions. The initial part of the first fraction was shown in an ELISA to contain IgM and to be devoid of IgG by immunoelectrophoresis and to have agglutinating activity (a titer of 1:4 with a protein concentration of 0.8 mg/ml). Treating this fraction with the reducing agent dithiothreitol (DTT) eliminated agglutinating activity. The latter portion of the second column fraction was shown to contain IgG by immunoelectrophoresis, and to be devoid of IgM by ELISA. Agglutinating activity was also present in the second fraction (a titer of 1:2 with a protein concentration of 1.9 mg/ml); hemagglutinating activity was not decreased by DTT treatment. These studies show that the predominant anti-A isoagglutinating activity in pooled sera from two blood type B cats is IgM and that some isoagglutinin activity can be associated with IgG.     

An abattoir survey of the prevalence of gastro-intestinal helminths andStephanurus dentatus in pigs in Belize

In an abattoir survey in Belize 137 pigs were examined for gastro-intestinal helminths and Stephanurus dentatus. Hyostrongylus rubidus, Physocephalus sexalatus, Globocephalus species and Trichostrongylus colubriformis were recorded for the first time. Ascarops strongylina, Ascaris suum, Macracanthorynchus hirudinaceus, Strongyloides ransomi, Trichuris suis, Oesophagostomum species and S. dentatus were also found. Oesophagostomum species (45%) and S. dentatus (42%) were the most prevalent. The prevalence of infection with different species was compared between pigs of different origin, breed and management. Differences were apparently due to management; most species were more common in poorly managed pigs. M. hirudinaceus and S. dentatus were used as "markers" to indicate poor management. The usual methods of faecal egg counting were found to be unreliable for the diagnosis of M. hirudinaceus infection.     

Host Range Studies for Tomato chlorosis virus, and Cucumber vein yellowing virus Transmitted by Bemisia tabaci (Gennadius)

The Bemisia tabaci (Gennadius) biotype B transmitted host range of Tomato chlorosis virus (ToCV), genus Crinivirus, Family Closteroviridae, and Cucumber vein yellowing virus (CVYV), genus Ipomovirus, Family Potyviridae, was studied. New experimental hosts were identified for each of these viruses. Seventeen species in eight plant families were assessed as potential hosts for ToCV. Infection in asymptomatic Anthriscus cereifolium (chervil) test plants by ToCV was confirmed by using a Real-Time PCR assay designed for ToCV. The presence of readily transmissible, infectious ToCV virions in A. cereifolium was confirmed by re-isolation of the virus via whitefly-transmission from A. cereifolium to Lycopersicon esculentum and A. cereifolium. This is the first report of the experimental transmission of ToCV by B. tabaci to a species within the Umbelliferae. All other hosts assessed for the presence of ToCV were found to be uninfected. Ten species in five families were assessed as potential hosts for CVYV. The CVYV host range identified included some important crops and common weeds, such as L. esculentum, Nicotiana tabacum, A. cereifolium, Datura stramonium, Nicotiana benthamiana, Nicotiana clevlandii and Cucumis sativus. Symptoms were present on D. stramonium, N. benthamiana and C. sativus control plants. The presence of infectious whitefly transmitted CVYV virions was confirmed solely for D. stramonium and N. tabacum, following re-isolation of the virus via B. tabaci transmission from all infected species to C. sativus. This is the␣first report of experimental CVYV transmission by B. tabaci to non-cucurbitaceous crop and weed hosts belonging to the Solanaceae or Umbelliferae.     

Tolerance to a non-host isolate of Verticillium dahliae in tomato

Tolerance to Verticillium spp. is a condition in which a host plant develops few symptoms despite substantial colonization by the pathogen. In the present paper we have shown that Craigella tomatoes are tolerant to a non-host isolate of V. dahliae, Dvd E6. Symptom expression was used to quantify disease and quantitative PCR to assess the amount of fungus in the stems. The classical incompatible and compatible interactions between Craigella resistant or Craigella susceptible near isolines and V. dahliae, race 1 were used for comparative purposes. Additional experiments using cytological assessment and quantitative PCR showed that in the tolerant interactions one plant defence response, vascular coating, was deployed as effectively as in resistant plants, limiting pathogen distribution. However, a second defence response, which causes the cyclical elimination of fungus from the stem in the classical interactions either does not occur or is substantially delayed in tolerant plants. Thus, the Verticillium population remains stable and substantial throughout the studied time course.     

确定食品保质期的理论和技术

作为衡量食品质量安全的一个重要指标，食品保质期越来越受到消费者和生产厂商的关注。本文从确定食品保质期的理论角度，介绍了加速破坏性实验、Weibull感官分析等实验方法，同时综述了国外近年来在食品保质期研究领域引入的一些新技术。     

Hypomagnesemia in 188 Dogs: A Hospital Population-Based Prevalence Study

Magnesium is a divalent cation involved in more than 300 metabolic processes. Magnesium acts as an intracellular regulator of most energy-demanding pathways. Clinical investigation in the human medical field has determined risk factors for hypomagnesemia and its relationship to a number of disease processes. Experimental studies have established the effects of hypomagnesemia in dogs, but little is known of its prevalence, risk factors, or clinical associations in a hospital population of dogs. To study the prevalence, risk factors, and clinical associations of hypomagnesemia in dogs, a retrospective cross-sectional study of dogs admitted to the University of Minnesota Veterinary Teaching Hospital over a 2.5-year period was undertaken. The prevalence of hypomagnesemia in the study population was 6.1% (188 of 3,102 dogs). Using both categorical and continuous variables in a univariate analysis, significant associations with hypomagnesemia were identified and used to construct a multivariate analysis of the relative risk of hypomagnesemia. Results from evaluation of 3,102 dogs indicate that the most significant predictors of hypomagnesemia were albumin ( P ≤ .0001; odds ratio [OR] = 0.2), potassium ( P ≤ .0001; OR = 0.5), total CO₂ ( P ≤.05; OR = 0.9), and blood urea nitrogen concentrations ( P < .0001; OR = 0.9), a diagnosis of cardiovascular disease ( P < .02; OR = 1.9); and being a Collie ( P < .02; OR = 3.9) or German Shepherd Dog ( P < .002; OR = 2.2). These results can be used to better understand and predict hypomagnesemia in dogs.     

Effects of chlordimeform on vascular smooth muscle

The effects of chlordimeform on agonist-induced contractions of rabbit aortic strips and on calcium flux in the deadventitiated strips have been studied. Chlordimeform antagonizes contractions induced by several vasoactive agents, with the order of antagonism being potassium . histamine > serotonin > norepinephrine, and decreases the rate of contraction of strips exposed to each of the four agonists. Muscles contracted by each of the agonists are rapidly relaxed by application of chlordimeform, although in the case of norepinephrine the relaxation only proceeds to approximately one-half of the maximal tension. The rate of washout of ⁴⁵Ca from the media-intimal layer of the rabbit aorta was increased by chlordimeform, but the norepinephrine-induced decrease in the rate of washout of ⁴⁵Ca was not affected by chlordimeform. Chlordimeform did not affect ⁴⁵Ca uptake by the media-intimal strips. The results of this study indicate that chlordimeform probably interferes with loosely bound calcium to a greater extent than it does with more tightly bound stores.