Synergistic Effects of Clostridium perfringens Enterotoxin and Beta Toxin in Rabbit Small Intestinal Loops

The ability of Clostridium perfringens type C to cause human enteritis necroticans (EN) is attributed to beta toxin (CPB). However, many EN strains also express C. perfringens enterotoxin (CPE), suggesting that CPE could be another contributor to EN. Supporting this possibility, lysate supernatants from modified Duncan-Strong sporulation (MDS) medium cultures of three CPE-positive type C EN strains caused enteropathogenic effects in rabbit small intestinal loops, which is significant since CPE is produced only during sporulation and since C. perfringens can sporulate in the intestines. Consequently, CPE and CPB contributions to the enteropathogenic effects of MDS lysate supernatants of CPE-positive type C EN strain CN3758 were evaluated using isogenic cpb and cpe null mutants. While supernatants of wild-type CN3758 MDS lysates induced significant hemorrhagic lesions and luminal fluid accumulation, MDS lysate supernatants of the cpb and cpe mutants caused neither significant damage nor fluid accumulation. This attenuation was attributable to inactivating these toxin genes since complementing the cpe mutant or reversing the cpb mutation restored the enteropathogenic effects of MDS lysate supernatants. Confirming that both CPB and CPE are needed for the enteropathogenic effects of CN3758 MDS lysate supernatants, purified CPB and CPE at the same concentrations found in CN3758 MDS lysates also acted together synergistically in rabbit small intestinal loops; however, only higher doses of either purified toxin independently caused enteropathogenic effects. These findings provide the first evidence for potential synergistic toxin interactions during C. perfringens intestinal infections and support a possible role for CPE, as well as CPB, in some EN cases.     

Adaptive optics imaging of the retina

Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) meetings. In total, 261 relevant publications and 389 conference abstracts were identified.     

HEPATOPROTECTIVE EFFECT OF AMOORA ROHITUKA

Abstract

Antihepatotoxic activity of a resuspended residue of the alcohol extract of Amoora rohituka W & A. (Meliaceae) was studied in rats with hepatic injury induced by carbon tetrachloride. Carbon tetrachloride (1 ml/kg, i.p.) was administered twice a week for 3 weeks and an extract of A. rohituka (50 mg/kg/day) was given orally for the same period. The rats were sacrificed 24 h after the last CC1₄ challenge. Carbon tetrachloride induced elevations of alkaline phosphatase (ALP), glutamate pyruvate transaminase (CPT), alanine aminotransferase (ALAT), glutamate oxaloacetate transaminase (GOT), aspartate aminotransferase (ASAT) and lactate dehydrogenase (LDH) and total plasma bilirubin concentration as well as depression of total plasma cholesterol concentration were reduced significantly by the concurrent treatment of rats with A. rohituka suspension. Changes in the histological architecture of the liver produced by CC1₄ where also protected by the administration of A. rohituka suspension. These results indicate that A. rohituka suspension possesses hepatoprotective action.