The recent ban on the use of antibiotics as a feed additive has led to the search for alternative sources of antibiotics in the feed industry. Presently, probiotics are considered as a potential substitute for antibiotic as a live biotherapeutic agent to improve animal health and performance. Accordingly, study was focused on evaluating the effect of Saccharomyces boulardii (Sb) and Bacillus subtilis B10 (Bs) on ultrastructure modulation and mucosal immunity development in broiler chickens. A total of three hundred 1-d-old Sanhuang broilers (a Chinese cross breed) were randomized into 3 groups, each group with 5 replications (n = 20). The control group (Ctr) was fed a basal diet containing an antibiotic (virginiamycin, 20 mg/kg). Meanwhile, broilers in experimental groups received Sb and Bs (1 × 10(8) cfu/kg of feed) in addition to the basal diet for 72 d. The results of the experimental groups revealed a significant improvement in live BW and relative weight of bursa of Fabricius and thymus. Also, intestinal villus height, width, and number of goblet cells increased in the Sb and Bs groups. Meanwhile, modulation in the intestinal ultrastructure and increased mRNA expression levels of occluding, cloudin2, and cloudin3 (P < 0.05) were observed in the Sb and Bs groups. Moreover, IgA-positive cells significantly increased in the jejunum of Sb- and Bs-supplemented groups (P < 0.05). Intestinal cytokines interleukin-6, tumor necrosis factor-α, interleukin-10, transforming growth factor-β, and secretory IgA concentrations were (P < 0.05) improved in the probiotic groups; however, Sb induced inflammatory and antiinflammatory cytokines (P < 0.05) in comparison with the Ctr group. The present findings conclusively revealed that Sb and Bs increased IgA-positive cells in the lumen of the intestinal villus and revealed that Sb and Bs could modulate intestinal ultrastructure through increasing occluding, cloudin2, and cloudin3 mRNA expression levels in broiler intestine.

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The increasing frequency of penicillin-resistant pneumococcus continues to be of concern throughout the world. Newer fluoroquinolone antibiotics, such as levofloxacin, have shown enhanced in vitro activity against Streptococcus pneumoniae. In this study, the bactericidal characteristics and pharmacodynamic profiles of levofloxacin, ciprofloxacin, and ampicillin against four isolates of S. pneumoniae were compared by using an in vitro model of infection. Standard antibiotic dosing regimens which simulated the pharmacokinetic profile observed in humans were used. Control and treatment models were sampled for bacterial CFU per milliliter over the duration of each 24-or 48-h experiment. In addition, treatment models were sampled for MIC determinations and drug concentration. Regrowth of all isolates as well as an increase in MICs throughout the study period was observed in the ciprofloxacin experiments. A limited amount of regrowth was noted during levofloxacin therapy for one isolate; however, no change in MIC was detected for any isolate. Ampicillin showed rapid and sustained bactericidal activity against all isolates. In this study, ratios of effective fluoroquinolone area under the concentration-time curve (AUC):MIC values ranged from 30 to 55. Levofloxacin, owing to its larger AUC 0-24 values, has excellent and sustained activity against different pneumococcal strains superior to that of ciprofloxacin.

Although growth hormone secretion decreases with age in both animals and man, its potential role in the regulation of biological aging is unknown. In a series of experiments, age-related changes in growth hormone secretory dynamics were compared in ad libitum fed and moderately calorically restricted male Brown-Norway rats. These animals exhibit an increase in both mean and maximal lifespan in response to caloric restriction. In addition, the subcellular distribution of somatostatin mRNA was compared since previous data indicated that somatostatin secretion increases with age and has an important role in the age-related decline in growth hormone pulse amplitude. In ad libitum fed animals, growth hormone secretory dynamics decreased with age and were associated with a decline in total somatostatin mRNA levels. However, analysis of somatostatin mRNA precipitating with polyribosomes revealed a significant increase with age (p < 0.05). When data were expressed as polysomal/total mRNA, levels in 25-month-old animals increased 94 and 104% compared to 6- or 16-month-old animals, respectively (p < 0.01). Growth hormone secretory dynamics decreased in young animals maintained on a moderate caloric restricted diet, but by 26 months growth hormone pulse amplitude increased and was indistinguishable from young ad libitum fed animals. In addition, the moderate caloric-restricted animals failed to exhibit the decline in total somatostatin mRNA or the increase in polyribosome-associated somatostatin mRNA characteristic of the ad libitum fed 25-month-old animals. Our results suggest that altered regulation of somatostatin mRNA at the translational level may be a contributing factor in the decrease in growth hormone secretion observed in aging animals. In addition, we conclude that part of the actions of moderate caloric restriction in delaying physiological changes associated with age are related to increased growth hormone secretion.