Pathophysiology of enteropathogenic Escherichia coli during a host infection

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhea in developing countries. However, sporadic outbreaks caused by this microorganism in developed countries are frequently reported recently. As an important zoonotic pathogen, EPEC is being monitored annually in several countries. Hallmark of EPEC infection is formation of attaching and effacing (A/E) lesions on the small intestine. To establish A/E lesions during a gastrointestinal tract (GIT) infeciton, EPEC must thrive in diverse GIT environments. A variety of stress responses by EPEC have been reported. These responses play significant roles in helping E. coli pass through GIT environments and establishing E. coli infection. Stringent response is one of those responses. It is mediated by guanosine tetraphosphate. Interestingly, previous studies have demonstrated that stringent response is a universal virulence regulatory mechanism present in many bacterial pathogens including EPEC. However, biological signficance of a bacterial stringent response in both EPEC and its interaction with the host during a GIT infection is unclear. It needs to be elucidated to broaden our insight to EPEC pathogenesis. In this review, diverse responses, including stringent response, of EPEC during a GIT infection are discussed to provide a new insight into EPEC pathophysiology in the GIT.     

EVALUATION OF DIAPHRAGMATIC MOTION IN NORMAL AND DIAPHRAGMATIC PARALYZED DOGS USING M‐MODE ULTRASONOGRAPHY

Diagnosis of unilateral diaphragmatic paralysis in dogs is currently based on fluoroscopic detection of unequal movement between the crura. Bilateral paralysis may be more difficult to confirm with fluoroscopy because diaphragmatic movement is sometimes produced by compensatory abdominal muscle contractions. The purpose of this study was to develop a new method to evaluate diaphragmatic movement using M‐mode ultrasonography and to describe findings for normal and diaphragmatic paralyzed dogs. Fifty‐five clinically normal dogs and two dogs with diaphragmatic paralysis were recruited. Thoracic radiographs were acquired for all dogs and fluoroscopy studies were also acquired for clinically affected dogs. Two observers independently measured diaphragmatic direction of motion and amplitude of excursion using M‐mode ultrasonography for dogs meeting study inclusion criteria. Eight of the clinically normal dogs were excluded due to abnormal thoracic radiographic findings. For the remaining normal dogs, the lower limit values of diaphragmatic excursion were 2.85–2.98 mm during normal breathing. One dog with bilateral diaphragmatic paralysis showed paradoxical movement of both crura at the end of inspiration. One dog with unilateral diaphragmatic paralysis had diaphragmatic excursion values of 2.00 ± 0.42 mm on the left side and 4.05 ± 1.48 mm on the right side. The difference between left and right diaphragmatic excursion values was 55%. Findings indicated that M‐mode ultrasonography is a relatively simple and objective method for measuring diaphragmatic movement in dogs. Future studies are needed in a larger number of dogs with diaphragmatic paralysis to determine the diagnostic sensitivity of this promising new technique.     

Cell proliferation and neuroblast differentiation in the dentate gyrus of high-fat diet-fed mice are increased after rosiglitazone treatment

In this study, we determined how rosiglitazone (RSG) differentially affected hippocampal neurogenesis in mice fed a low-fat diet (LFD) or high-fat diet (HFD; 60% fat). LFD and HFD were given to the mice for 8 weeks. Four weeks after initiating the LFD and HFD feeding, vehicle or RSG was administered orally once a day to both groups of mice. We measured cell proliferation and neuroblast differentiation in the subgranular zone of the dentate gyrus using Ki67 and doublecortin (DCX), respectively, as markers. In addition, we monitored the effects of RSG on the levels of DCX and brain-derived neurotrophic factor (BDNF) in hippocampal homogenates. At 8 weeks after the LFD feeding, the numbers of Ki67- and DCX-positive cells as well as hippocampal levels of DCX and BDNF were significantly decreased in the RSG-treated group compared to the vehicle-treated animals. In contrast, the numbers of Ki67- and DCX-positive cells along with hippocampal levels of DCX and BDNF in the HFD fed mice were significantly increased in the RSG-treated mice compared to the vehicle-treated group. Our data demonstrate that RSG can modulate the levels of BDNF, which could play a pivotal role in cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus.     

Comparative study of ultrasonography and arteriography of the carotid artery of xylazine-sedated and halothane-anesthetized goats

The carotid artery of clinically normal goats was examined, using duplex ultrasonography and arteriography. The diameter of the carotid artery was measured by use of two-dimensional ultrasonography and Doppler ultrasonography, respectively, before and after xylazine administration. The diameter of the artery was also measured by use of an arteriography technique in halothane-anesthetized goats. There was no significant difference between the mean diameter of the carotid artery measured by ultrasonography in conscious nonsedated goats and that determined by arteriography in goats under halothane anesthesia. On the other hand, ultrasonography of xylazine-sedated goats revealed an increase of carotid artery diameter of 20 to 30%. There was no change in the velocity of blood flow after xylazine administration.     

IMMUNITY TO EXPERIMENTAL STAPHYLOCOCCAL MASTITIS—COMPARISON OF LIVE AND KILLED VACCINES

SUMMARY Eleven pregnant Merino ewes were immunised with either a killed Staphylococcus aureus cell-toxoid vaccine (intramuscularly) or a living culture of the same organism (subcutaneously). A further 3 animals were used as non-immunised controls. There were no significant differences between the vaccinated groups for agglutinating antibody to staphylococci or for anti-α-haemolysin in either serum or whey. Three weeks after lambing the ewes were challenged by intramammary infusion of virulent staphylococci. All animals developed an acute mastitis with significant decreases in milk yields being recorded 48 hours post-challenge. Seven days after challenge the mean milk production of ewes given the live vaccine had recovered to within 5% of the pre-challenge mean yield. However, milk productions of controls and ewes given the killed vaccine had further decreased and were significantly lower than for animals vaccinated with live staphylococci. There were no significant differences between the two vaccinated groups for numbers of bacteria or leucocytes in milk samples collected after challenge. The ewes were killed 7 days postchallenge and mammary tissues were examined for immunoglobulin-containing cells. Large numbers of IgA-containing cells, and few IgM-containing cells were found, but there were no significant differences between the treatment groups for these parameters.     

Evaluation of canine gastric motility with ultrasonography

For the evaluation of canine gastric motility with ultrasonography, contraction number of pyloric antrum and gastric emptying time (GET) by area and volume method developed by Bolondi et al.'s method were studied in 14 dogs. All experimental dogs were administered with saline and soup solution (10 ml/kg, B.W.). The mean values of contraction number of pyloric antrum in saline and soup group were 4.19 +/- 1.30/min and 4.82 +/- 0.65/min before feeding, and overall mean values were 4.66 +/- 1.37/min and 5.13 +/- 1.71/min, respectively. The mean values of the GET by area and volume method were 36.73 +/- 11.27, 40.00 +/- 8.87 min in saline group and 61.35 +/- 17.58, 59.11 +/- 14.46 min in soup group. In the GET in saline and soup groups, there was no significant difference between the area and volume method (p>0.05). Therefore, Bolondi et al.'s method by ultrasound can be used to evaluate the antropyloric motility and gastric emptying time with area and volume methods. The area method is easier to determine the GET than the volume method, but the latter is more accurate.     

Serodiagnostic comparison of enzyme-linked immunosorbent assay and surface plasmon resonance for the detection of antibody to Porcine circovirus type 2

This paper describes the cloning and expression of the capsid protein of Porcine circovirus type 2 (PCV2) in an Escherichia coli expression system that was used to produce a fusion protein for subsequent immunologic studies: enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR). Polymerase chain reaction was used to amplify the gene encoding the capsid protein from the DNA of PCV2. The protein was then cloned into a pRSET prokaryotic expression vector. Western blot analysis revealed that the recombinant protein gave strong signals on a polyvinylidene difluoride membrane when exposed to the serum from a pig infected with PCV2. The expressed protein was purified and used as an antigen for the ELISA and SPR study. A protein chip based on SPR was developed, and the diagnostic potential of SPR was compared with that of ELISA with the use of 70 serum samples obtained from 6 pig farms. There was a strong positive correlation between the ELISA and SPR titers (r = 0.877, P < 0.01). Therefore, this recombinant capsid protein can be used as an antigen for serologic studies, and the SPR, a label-free method, appears to be a valuable and reproducible tool in the serodiagnosis of a PCV2 infection.     

Chronology of development of serum antispirochete antibody in swine experimentally exposed to swine dysentery: preliminary report.

By using an indirect fluorescent antibody test (with immunofluorescence of large spirochetes as positive), serum antispirochete antibodies were detected initially at 4 weeks after onset of diarrhea in swine exposed to infective swine dysentery inoculum. Antibodies continued to be present in serum of swine tested 5 months after onset of diarrhea.