Characterization of cytotoxic factors of Yersinia pseudotuberculosis using the MDBK cell line.

The cytotoxin of four strains of Yersinia pseudotuberculosis was characterized using the MDBK cell line and by application of the MTT colorimetric test. The highest cytotoxin yield was obtained in tryptic soy broth medium after 24 h. It was detected in the cell-free culture filtrate, and treatment of the cells with CHAPS as a membrane detergent did not decrease significantly their cytotoxic activity. The cytotoxin was inhibited by trypsinization and by increasing values of either acidity or alkalinity. The cytotoxin was inactivated partially by heating at 70 degrees C for 20 min and totally at 90 degrees C for 10 min. The results obtained indicate that the cytotoxin is protein in nature and produced mainly as free exotoxin.

Serum sensitivity and apathogenicity for chickens and chick embryos of Escherichia coli J5 strain.

Escherichia coli J5 strain was assessed for its serum resistance and pathogenicity for both chickens and chick embryos. Pathogenicity for chickens was assessed by intravenous inoculation into three-week-old broiler chickens. Pathogenicity for chick embryos was determined by inoculation of 12-day-old chick embryos into the allantoic cavity. Chicken serum was used to determine the serum resistance status. E coli J5 strain was found to be serum-sensitive and apathogenic for chickens and chick embryos. No mortality and no gross lesions occurred in the chickens inoculated with this strain. The chick embryos inoculated with this strain remained alive. It is worth trying this strain as a live vaccine to immunize chickens against infection from different serotypes of E coli.

Pathogenicity of Enterococcus hirae for chicken embryos and betamethasone-treated chicks.

An isolate Enterococcus hirae was used to determine its pathogenicity for chicken embryos and for chicks treated with betamethasone. E hirae was inoculated intravenously into four-day-old chicks which had been treated for three consecutive days with betamethasone, and chick embryos were inoculated into the allantoic cavity with 10(2) and 10(3) bacteria. E hirae was not pathogenic for the chicks or for the embryos.

Effect of Honey on Bacterial Growth and Spore Germination.

The effect of honey on the growth of Bacillus cereus , Staphylococcus aureus , Salmonella dublin and Shigella dysenteriae was examined in this study. Gram-positive bacteria were found to be less sensitive to the inhibitory action of honey compared to gram-negative bacteria. Significant growth inhibition (p<0.05) of S. dublin and S. dysenteriae was obtained by using 2% (vol/vol) honey. Spore germination of B. cereus was also significantly inhibited (P<0.05) by 2% (vol/vol) honey. The inhibitory factor(s) is under investigation.

Seroprevalence of Toxocara canis antibodies in humans in northern Jordan.

Sera of 699 individuals, aged between 5-24 years, from the Irbid area, Jordan, were tested for Toxocara canis antibodies using an ELISA-IgG test. Crude prevalence was 10.9% (76 of 699) but age-adjusted prevalence was 14.3%. The highest prevalence was observed in females aged 5-9 years, 23.3% (7 of 30), and males of 15-19 years of age, 19.5% (16 of 82). The lowest prevalence was observed in females aged 20-25 years, 5.2% (8 of 155). Significant differences (P < 0.05) between the prevalences of the toxocaral antibodies in males and females were observed in the age groups 5-9, 15-19 and 20-24 years. The trend of prevalence in relation to age was different according to sex.

Detection of proteins after immunoblotting on nitrocellulose using fluorescent antibodies.

A Western blot method is described utilizing 5-dimethylaminonaphthalene-1-sulfonyl (dansyl chloride)-conjugated antibodies to detect proteins transferred onto nitrocellulose. Four proteins of different molecular weight, including human albumin, gamma heavy chain, kappa and lambda light chains of immunoglobulins, were tested. Labeling with the fluorochrome was compared with the method of enzyme-conjugated antibodies and was found to have similar sensitivity, specificity, and safety. Moreover, this method is less expensive, and the labeled antibodies can be prepared fresh in a short time and are free from the disadvantages of enzyme label whose activity is affected by the presence of activators or inhibitors in the tested specimens.

Electrophoretic elution of macromolecules from polyacrylamide or agarose gels.

A method for elution of micrograms of macromolecules from polyacrylamide and agarose gels is described. The recoveries were greater than 90% with three different macromolecules tested (28 to 360 kDa). An amount as small as 1 microgram of human serum albumin was eluted from polyacrylamide gel with 90% recovery. The eluted material is collected into a small chamber the size of which can be changed as required. Elution and concentration are achieved simultaneously and in one step under mild conditions. Sterile eluates can be obtained, if the apparatus is constructed under sterile conditions.

Immune status of young adults to mumps virus infection in northern Jordan.

Eight hundred and seventy-five sera, collected randomly from university students aged 18-24 years, were tested for mumps virus antibodies. The prevalence of seropositivity was 85.3% for males and 87.1% for females using the enzyme linked immunosorbent assay method (ELISA) and 83.4% for males and 77.6% for females using the micro-complement fixation test (CFT). The remaining 14.7%-16.7% of males and 12.9%-22.3% of females, who had non-reactive sera in ELISA and CFT tests respectively indicated the presence of a sizeable population with a high risk of contracting the infection and this recommends the implementation of routine vaccination against mumps in Jordan. The two techniques correlated well, though ELISA exhibited a higher sensitivity than CFT.