Polyviewed expression of the altered contractility of the guinea-pig ileum after ischemia in situ and superfusion in vitro.

This study deals with the polyviewed expression of the altered contractility of the isolated ileum of the guinea-pig after ischemia/superfusion (I/S). Intestinal ischemia was produced by clamping the superior mesenteric artery for 40, 80 or 160 min. Ischemic and non-ischemic segments taken from the same guinea-pig were mounted for tension recording in organ baths and superfused (120 min) with an oxygenated Krebs-bicarbonate solution. Data were analyzed by means of the Polyview System software, which allows detecting simultaneously several events of one response. Histopathological changes in myenteric neurons were also examined. We found that ischemia in situ followed by superfusion in vitro (reoxygenation) severely reduces the spontaneous intestine contractile activity, and significantly decreases the maximal contractile response to ACh and to electrical field stimulation (EFS), the maximal rate of tension, and the sensitivity of the tissue to EFS. In addition, these ischemic intestines respond with a long-lasting contracture when electrical stimulation was started at supramaximal voltage. Functional alterations were time dependent. Neurons exhibited features of necrosis. These results provide clear evidence of detrimental effects of I/S on intestine contractile function. Digital analysis allows quantification of additional parameters important for evaluation of functional changes after I/S and of the degree of neuroprotection.

Cloning and expression of DiT33 from Dirofilaria immitis: a specific and early marker of heartworm infection.

Dirofilaria immitis is an important filarial parasite of dogs and cats, and a useful model for human filariasis. Current diagnostic tests for heartworm infection in animals rely on the presence of fecund female worms (usually found 6.5 months post-infection or later) and therefore fail to detect pre-patent infections. Putative pepsin inhibitors from 2 filarial parasites of humans namely Onchocerca volvulus (Ov33, Oc3.6, OvD5B) and Brugia malayi (Bm33), have been shown to be useful in diagnosis of onchocerciasis and lymphatic filariasis, respectively. Previous studies have suggested that a homologue exists in D. immitis (DiT33), which may have potential in diagnosis of heartworm infection. In this study, the isolation and characterization of a cDNA clone encoding DiT33 is described. This cDNA contains 12 bases of the nematode-specific 22 nucleotide spliced leader sequence and encodes a 26.4 kDa-protein with a high level of similarity (87-89%) to other filarial members of the family. DiT33 was over-expressed in E. coli as a fusion with the maltose-binding protein and serological analysis was performed using a panel of clinically defined dog sera. The findings of this study indicate that DiT33 is a promising antigen for the early detection of D. immitis and may be a valuable tool in the control and management of heartworm infection.

Expression of an Onchocerca volvulus Ov33 homolog in Dirofilaria immitis: potential in immunodiagnosis of heartworm infection.

In this study, the expression of an Onchocerca volvulus Ov33 homolog was demonstrated in Dirofilaria immitis. Rabbit antiserum raised against a recombinant fusion protein of O. volvulus, MBP/OvD 5B (Ov33), was found to react with a 31-33 kDa glycoprotein (DiT33) of adult worms of D. immitis. An antibody response to MBP/OvD 5B was observed in dogs, as early as 11 weeks post infection with infective larvae of D. immitis, and in dogs with occult infection. Cats both experimentally and naturally infected with D. immitis also reacted strongly with the recombinant antigen. In contrast, sera from dogs receiving chemically-abbreviated infection or from animals harbouring a variety of other helminths failed to react. These data suggest that antibody responses generated by DiT33 may have potential in immunodiagnosis of heartworm infection in cats and dogs.