Construction and evaluation of type III secretion system mutants of the catfish pathogen Edwardsiella piscicida.

Catfish is the largest aquaculture industry in the United States. Edwardsiellosis is considered one of the most significant problems affecting this industry. Edwardsiella piscicida is a newly described species within the genus Edwardsiella, and it was previously classified as Edwardsiella tarda. It causes gastrointestinal septicaemia, primarily in summer months, in farmed channel catfish in the south-eastern United States. In the current study, we adapted gene deletion methods used for Edwardsiella to E. piscicida strain C07-087, which was isolated from a disease outbreak in a catfish production pond. Four genes encoding structural proteins in the type III secretion system (T3SS) apparatus of E. piscicida were deleted by homologous recombination and allelic exchange to produce in-frame deletion mutants (EpΔssaV, EpΔesaM, EpΔyscR and EpΔescT). The mutants were phenotypically characterized, and virulence and vaccine efficacy were evaluated. Three of the mutants, EpΔssaV, EpΔyscR and EpΔesaM, were significantly attenuated compared to the parent strain (p < .05), but EpΔescT strain was not. Vaccination of catfish with the four mutant strains (EpΔssaV, EpΔesaM, EpΔyscR and EpΔescT) provided significant protection when subsequently challenged with wild-type strain. In conclusion, we report methods for gene deletion in E. piscicida and development of vaccine candidates derived from a virulent catfish isolate.

Gastrointestinal manifestations in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune disorder characterized by multisystem involvement, including the gastrointestinal (GI) tract. There is a significant variation in the clinical presentation and severity of GI disorders. When GI symptoms present as the initial manifestation of SLE, there is likely to be a delay in the diagnosis. The cause of these GI manifestations in SLE may be the disease, or the side effects of medications, or infections. In this study we investigated the GI manifestations in a group of SLE patients. Our study was conducted on 40 SLE patients and 30 healthy controls to assess the prevalence of GI symptoms in SLE patients. The prevalence of gastrointestinal manifestations in our study was 42.5%. GI manifestations in our SLE patients were: acute abdominal pain (due to pleurisy and peritonitis), 6%; diffuse abdominal pain, 23.5%; epigastric pain, 29%; epigastric pain with vomiting, 23.5%; epigastric pain with chronic constipation, 6%; chronic constipation, 6%; and diffuse abdominal pain with bleeding per rectum, 6%. In our study, we found a higher incidence of Giardia infestation in SLE patients than in healthy controls, and 10% of these patients were asymptomatic. There was more Giardia infestation in patients with GI symptoms as compared with patients with no GI symptoms, with a P value of 0.009. In our study SLE patients with GI symptoms had a peak systolic velocity (cm/s) with a mean of 108.4 ± 32.1 standard deviation (SD) in the celiac Doppler study. Patients without GI symptoms had a peak systolic velocity with a mean of 111.9 ± 37.7 SD, meaning that our patients mostly had no evidence of celiac trunk stenosis, but there was significant difference between SLE patients without GI symptoms and controls, as the mean was higher in SLE patients than in the controls. Also, the celiac end diastolic velocity was higher in both groups of SLE patients with GI symptoms and those without GI symptoms, compared to controls.

Smith-Lemli-Opitz syndrome among Arabs.

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive disorder of variable presentation caused by the deficiency of the 3ß- hydroxycholesterol Δ(7) - reductase. Over the past 10 years, our biochemical laboratory has screened 191 plasma samples for possible SLOS, measuring the plasma cholesterol and 7-dehydrocholesterol using gas chromatography-mass spectrometry (GC-MS). The SLOS was confirmed in only five Arab patients with growth retardation, global developmental delay, dysmorphic features, and 2-3 toe syndactyly, among other findings. All cases represented moderate to severe form of SLOS. One patient had a unique cardiovascular malformation (cor triatriatum with significant obstruction of the right pulmonary veins). Two previously reported N287K (861 C>A) and R352Q (1055 G>A) and a novel R352L (1055 G>T) mutations were identified in the DHCR7 gene in these patients. The paper sheds light on this rare disease among Arabs and reviews all reported SLOS cases in the Arab population.

Anti-tumor necrosis factor (TNF) therapy in rheumatoid arthritis: correlation of TNF-alpha serum level with clinical response and benefit from changing dose or frequency of infliximab infusions.

OBJECTIVE: To determine the relationship between serum TNF-alpha level and clinical response in rheumatoid arthritis patients treated by infliximab. This could be of value to predict clinical response to infliximab and to determine the optimal dose and interval between dosing of infliximab. RA patients who did not respond adequately to conventional doses (3 mg/kg) of infliximab were studied to see if increasing the dose or frequency of infliximab infusions would be more effective. METHODS: Fifty-five RA patients who fulfilled the American College of Rheumatology criteria and were receiving treatment by anti-TNF-alpha (infliximab 3 mg/kg body weight every 8 weeks) were evaluated by: clinical disease activity using the Richie score index before receiving their scheduled infliximab infusion. Serum level of TNF-alpha, as measured by competitive ELISA assay, was determined immediately before and 9-11 days after receiving infliximab. RA patients who did not respond adequately to treatment with infliximab were given either a larger dose of infliximab or given the infusion at six-week intervals. Their clinical response was then evaluated sixteen months later. RESULTS Patients were divided into 2 groups according to Richie score, active group with score > 10 (score 20.3 +/- 7.7 mean +/- standard deviation, n = 25) and inactive group with scores < or = 10 (score 4.1 +/- 3.2, n = 30). TNF-alpha serum levels pre-infliximab infusion were significantly higher in the active group 76.1 pg/ml than the inactive group 38.0 pg/ml (P < 0.02). Whereas TNF serum level significantly dropped post infliximab in the inactive group (P < 0.05), it did not drop in the active group. The mean level of the post-infusion TNF-alpha serum level was higher (76.6 +/- 93.4 ng/ml) in the-active than the mean level of the post-infusion serum TNF-alpha levels in the inactive group (26.4 ng/ml +/- 7.9) P < 0.01 using the t-test. Increasing the frequency was superior in RA patients' clinical outcome than increasing the dose of infliximab infusions. CONCLUSION: RA patients who responded well to infliximab and had inactive disease at the time of the study have lower levels of serum TNF-alpha which could be further suppressed by the recommended doses of infliximab. RA patients with active disease have higher serum levels of TNF-alpha which could not be suppressed after the recommended doses of infliximab infusion. Changing the frequency of infliximab infusions in the active group was more effective than increasing the dose of infliximab in inducing improved clinical outcome. We suggest that the lack of suppression of TNF-alpha in the active group could be due to inadequate dosing of infliximab or to the presence of a neutralizing antibody directed against infliximab. It remains to be seen if serum TNF-alpha levels could be used as a guide in determining the dose and intervals between dosing of anti-TNF therapy in RA in order to achieve the desired clinical response.