Somatotropin and adipose tissue metabolism: substrate and temporal effects

The purpose of these studies was to determine the time course for changes in feed intake, blood metabolites, and lipogenic activity in adipose tissue in response to the initiation of porcine somatotropin (pST) treatment and following withdrawal from treatment in barrows. An initial study was conducted to determine the impact of chronic pST treatment (4 wk of daily injection; 0 vs 4 mg/d) on adipose tissue lipid metabolism in barrows (initial weight 67 kg). Feed efficiency was improved 27%, backfat thickness was decreased 43%, and glucose and lactate oxidation and incorporation into lipid in adipose tissue was reduced 70 to 86% in pST-treated pigs. Palmitate esterification was decreased 44%, whereas palmitate oxidation was unaffected. In vitro metabolism of lactate, glucose, and palmitate in liver slices was not affected by pST treatment. The time-course for changes in intake and adipose tissue metabolism in response to 7 d of pST (0 vs 4 mg/d) treatment and 7 d of withdrawal was examined in subsequent studies in barrows (initial weight 75 kg). Feed intake during pST treatment was significantly (P < .05) less than in control pigs within 24 h of the initiation of treatment and remained low through 3 d after withdrawal. Adipose tissue biopsies were obtained on d 0, 1, 2, 4, and 7 of the treatment phase and on d 2, 4, and 7 after withdrawal from 7 d of treatment. Maximal inhibition of lipogenesis by pST treatment in adipose tissue in vitro was observed on d 4 (-68%) and d 7 (-69%). Similarly, fatty acid synthase activity declined during the treatment period, with the greatest change noted on d 7 (-26%). After withdrawal from treatment, lipogenesis gradually increased, returning to control values 7 d after withdrawal. Levels of IGF-I began to increase from d 1 to d 7 of treatment, continually decreased during withdrawal, and were normalized by the end of the withdrawal period. Plasma urea nitrogen concentrations decreased during treatment, increased during the withdrawal phase, and were normalized 4 d after the last pST treatment. Overall results indicate that most of the metabolic changes in response to pST occur within 1 wk of treatment and return to pretreatment values after 7 d of withdrawal from treatment.     

Characterization of culture supernatant proteins from Brucella abortus and its protection effects against murine brucellosis

In this study, we characterized the secreted proteins of Brucella abortus into the enriched media under the bacterial laboratory growth condition and investigated the pathogenic importance of culture supernatant (CS) proteins to B. abortus infection. CS proteins from stationary phase were concentrated and analyzed using 2D electrophoresis. In MALDI TOF/TOF analysis, more than 27 proteins including CuZn SOD, Dps, Tat, OMPs, Adh, LivF, Tuf, SucC, GroEL and DnaK were identified. Cytotoxic effects of CS proteins were found to increase in a dose-dependent manner in RAW 264.7 cells. Upon B. abortus challenge into phagocytes, however, CS proteins pre-treated cells exhibited lower bacterial uptake and intracellular replication compared to untreated cells. Immunization with CS proteins induced a strong humoral and cell mediated immune responses and exhibited significant higher degree of protection against virulence of B. abortus infection compared to mice immunized with Brucella broth protein (BBP). Taken together, these results indicate that B. abortus secreted a number of soluble immunogenic proteins under laboratory culture condition, which can promote antibody production resulted in enhancing host defense against to subsequently bacterial infection. Moreover, further analysis of CS proteins may help to understand the pathogenic mechanism of B. abortus infection and host–pathogen interaction.     

Antimicrobial resistance of Escherichia coli O26 and O111 isolates from cattle and their characteristics

The present study was to investigate antimicrobial resistance profiles of Escherichia coli O26 and O111 from cattle and to characterize the virulence genes of the resistant isolates. This paper reports the high prevalence of antimicrobial resistant E. coli O26 and O111 from cattle. Among 37 E. coli O26 and 25 E. coli O111 isolates from the fecal specimens obtained from cattle, 26 (70%) and 15 (60%) were resistant to at least one antibiotic, respectively. Forty (98%) of the 41 resistant isolates were resistant to two or more antibiotics. Among the 22 antibiotics tested in this study, ampicillin was the most common antibiotic that the isolates were resistant to, followed by tetracycline and streptomycin. None of the isolates were resistant to fluoroquinolones, such as ciprofloxacin, ofloxacin and norfloxacin, and to ceftriaxone, amikacin and imipenem. Eighteen different resistant types among the 41 isolates were observed by the cluster analysis. The most frequent antibiotic-resistance type was ampicillin-tetracycline-streptomycin-cephalothin-sulfisoxazole-ticarcillin-kanamycin-minocycline-piperacillin-chloramphenicol, which accounted for 9 (22%) of the resistant isolates. The observation of frequent and multiple resistances to antibiotics highlights the need for their careful use if their benefits are to be preserved. PCR analysis of the EHEC virulence markers showed that 25 of the resistant E. coli O26 and O111 isolates tested positive for stx2 or both stx1 and stx2. This suggests that the majority of these isolates can cause serious diseases in humans and may complicate the future therapeutic options under development.     

Occurrence and characteristics of enterohemorrhagic Escherichia coli O26 and O111 in calves associated with diarrhea

The aims of this study were: (1) to examine whether or not enterohemorrhagic Escherichia coli O26 and O111 (EHEC O26 and O111) are involved in neonatal calf diarrhea; (2) to determine the specific age periods at which the calves are vulnerable to these organisms, and (3) to reveal the biochemical, genetic and cytotoxic characteristics of the isolates. The study investigated the occurrence of EHEC O26 and O111 in calves associated with or without diarrhea. A total of 442 diarrheic and non-diarrheic young calves from 115 different farms were examined. Of the 257 calves with diarrhea, 37 (14.4%) and 32 (12.5%) tested positive for EHEC O26 and EHEC O111, respectively. Of the 185 non-diarrheic calves, 14 (7.6%) and 11 (5.9%) tested positive for EHEC O26 and EHEC O111, respectively. EHEC O26 and O111 were recovered from 14/69 (20%) and 11/69 (16%) diarrheic calves <2-weeks-old, respectively, and no EHEC O26 and O111 were detected in the non-diarrheic claves of this age group, suggesting that EHEC O26 and O111 are possible causes of the disease in infected neonatal calves. However, there were similar rates of occurrence in the diarrheic and non-diarrheic calves in the older animals (particularly, aged >10 weeks). PCR analysis showed that the isolates carried various virulence genes such as Ehly, eae, stx1 and stx2, which highlight the potential importance of these attributes for the infection, colonization and the possible pathogenesis of calf diarrhea. Cytotoxicity analysis revealed that many of the EHEC isolates showed high cytotoxicity to Vero cells, re-emphasizing the potential for cattle being a direct source of EHEC infections in humans.     

Effect of body weight on the pharmacokinetics of flunixin meglumine in miniature horses and quarter horses

In most species, large variations in body size necessitate dose adjustments based on an allometric function of body weight. Despite the substantial disparity in body size between miniature horses and light‐breed horses, there are no studies investigating appropriate dosing of any veterinary drug in miniature horses. The purpose of this study was to determine whether miniature horses should receive a different dosage of flunixin meglumine than that used typically in light‐breed horses. A standard dose of flunixin meglumine was administered intravenously to eight horses of each breed, and three‐compartmental analysis was used to compare pharmacokinetic parameters between breed groups. The total body clearance of flunixin was 0.97 ± 0.30 mL/min/kg in miniature horses and 1.04 ± 0.27 mL/min/kg in quarter horses. There were no significant differences between miniature horses and quarter horses in total body clearance, the terminal elimination rate, area under the plasma concentration versus time curve, apparent volume of distribution at steady‐state or the volume of the central compartment for flunixin (P > 0.05). Therefore, flunixin meglumine may be administered to miniature horses at the same dosage as is used in light‐breed horses.     

Detection and characterization of bovine-like coronaviruses from four species of zoo ruminants

Five coronaviruses (CoVs) were detected in diarrheal feces from four zoo ruminant species: one wisent (Bison bonasus), two Himalayan tahr (Hemitragus jemlahicus), one sitatunga (Tragelaphus spekii), and one nyala (Tragelaphus angasii). We sequenced and analyzed the spike (S) and hemagglutinin/esterase (HE) genes of these viruses and compared the nucleotide (nt) and deduced amino acid (aa) sequences with those of other bovine CoV (BcoV) strains. Comparison of the entire deduced aa sequences of the S and HE glycoproteins revealed no specific differences that would account for discrimination between bovine-like CoV strains from zoo ruminants and BcoVs strains. In addition, the 99.9% aa identity among the five CoV strains revealed that the ruminants were infected by the same strain. Phylogenetically, bovine-like CoVs belong to group 2a CoVs, which are related most closely to the BcoV strains recently isolated in Korea. These data suggest that cattle are potential reservoirs for CoVs that are capable of infecting zoo ruminants.     

Immune responses to new vaccine candidates constructed by a live attenuated Salmonella Typhimurium delivery system expressing Escherichia coli F4, F5, F6, F41 and intimin adhesin antigens in a murine model

To construct a novel live oral vaccine candidate for the prevention of pathogenic Escherichia coli infections in neonatal piglets, an expression and secretion plasmid and an attenuated Salmonella delivery system were used. The individual E. coli genes K88ac, K99, FasA, F41 and intimin adhesins were inserted into pBP244 containing asd, lepB, secA and secB, and these plasmids were transformed into a Salmonella Typhimurium ΔcpxR Δlon Δasd. Forty female BALB/c mice were divided into four groups, A to D (ten mice per group). Groups A and B were administered with the mixture containing all constructs and the S. Typhimurium containing pBP244 only as a control, respectively. Groups C and D were primed and boosted with the mixture and the S. Typhimurium harboring pBP244 only, respectively. Each recombinant adhesin secreted from the individual candidates was confirmed by Western blot analysis. The serum IgG and secretory IgA (sIgA) titers to individual adhesins in all immunized groups were higher than those in control. Furthermore, IgG and sIgA levels in group C were higher than those in group A, and the IgG1 titers were increased in Group C but IgG2a titers were similar or decreased in Group C compared to Group A. In addition, the vaccine strains were not detected in fecal samples of any immunized mice. The novel vaccine candidates are not only highly immunogenic, but also safe for vaccinated mice and environment. In addition, the immune responses can be more efficiently induced through the booster-administration.