"Tubules-Within-a-Tubule" Hierarchical Order of Mesoporous Molecular Sieves in MCM-41

The recently discovered mesoporous aluminosilicate MCM-41 consists of hexagonal arrays of nanometer-sized cylindrical pores. It is shown that this material can be synthesized by cooperative condensation of silicate and cylindrical cationic micelles. Careful control of the surfactant-water content and the rate of condensation of silica at high alkalinity resulted in hollow tubules 0.3 to 3 micrometers in diameter. The wall of the tubules consisted of coaxial cylindrical pores, nanometers in size, that are characteristic of those of MCM-41. The formation of this higher order structure may take place through a liquid crystal phase transformation mechanism involving an anisotropic membrane-to-tubule phase change. The hierarchical organization of this "tubules-within-a-tubule" particle texture is similar to that of the frustules of marine diatoms.     

Parenteral immunization of pigs against infection with Treponema hyodysenteriae.

Six intravenous injections of formalin-inactivated Treponema hyodysenteriae were given to 8 specific-pathogen-free pigs at 6-day intervals. The 8 vaccinated and 8 control pigs were challenged intragastrically with pure cultures of T hyodysenteriae 7 and 8 days after the last intravenous injection. Clinical signs of swine dysentery were observed in all 8 control pigs, but was observed in only 1 of the immunized pigs. Three control pigs died. These findings suggest that parenteral immunization with T hyodysenteriae provided a marked degree of protection against subsequent intragastric challenge exposure with the homologous isolate of T hyodysenteriae.     

Necrotic enteritis-producing strains of Clostridium perfringens displace non-necrotic enteritis strains from the gut of chicks

We inoculated broiler chicks with mixtures of Clostridium perfringens strains to investigate the single strain dominance observed in natural cases of necrotic enteritis (NE) [Nauerby, B., Pedersen, K., Madsen, M., 2003. Analysis by pulsed-field gel electrophoresis of the genetic diversity among Clostridium perfringens isolates from chickens. Vet. Microbiol. 94, 257-266]. Pre-inoculation bacteriologic culture of chick intestines yielded up to six pulsed-field gel electrophoresis (PFGE) types of C. perfringens. Birds developed typical NE lesions in response to administration (2x per day for 4 days) of a combined inoculum comprising one NE strain (JGS4143, PFGE pattern 8) and four non-NE strains (from piglet necrotizing enteritis, chicken normal flora, human gas gangrene, and bovine neonatal enteritis). After inoculation commenced, only the NE strain was recovered through the first post-inoculation day, in spite of intense efforts to recover pre-challenge flora strains and the other challenge strains. Thereafter, pre-inoculation and previously undetected PFGE types were found, and JGS4143 became undetectable. Birds inoculated simultaneously with five NE strains (from disease in chickens or turkeys, and including JGS4143) also developed lesions, but again only JGS4143 was recovered through the 1st day post-challenge. At that time, birds began to be repopulated with pre-challenge PFGE types. Two NE strains (JGS4143 and JGS4064) produced bacteriocins, which inhibited each other and normal flora strains (n=17), while normal flora strains inhibited neither NE strains nor each other. Thus, it appears that naturally occurring dominance of the gut by NE strains can be reproduced experimentally. Bacteriocins directed against normal flora could possibly provide the necessary advantage, although inhibition of one NE strain by another suggests that other factors may be partially or completely responsible for the dominance.     

An outbreak of type C botulism in 12 horses and a mule

A USDA Early Response Team investigated deaths of several horses and a mule in northern Arizona at the request of local animal health officials. Thirteen animals (12 horses and 1 mule) housed at 5 facilities in a 7.4 square mile area died between August 1998 and January 1999. Clinical signs consisted of muscular weakness that rapidly progressed to lateral recumbency. Ten animals had paresis of the tongue, throat, or lips. Affected animals appeared alert and were interested in eating and drinking, even while recumbent. All 13 animals were euthanatized. Clostridium botulinum type C was isolated from feces or intestinal contents from 3 affected horses. Preformed toxin was detected in samples of soil and bird droppings collected from a nearby horse burial site. It was hypothesized that the outbreak was a result of birds, presumably ravens, feeding at the burial site and at horse facilities in the area that transferred toxin to the affected animals.     

Experimental reproduction of porcine proliferative enteritis

Conventional crossbred pigs from different sources and of different weights were examined for susceptibility to porcine proliferative enteritis. The ileal mucosa of pigs with the disease was emulsified and suspended in Mueller-Hinton broth. Pigs weighing 15, 120 and 200 lb (6.8, 54.5 and 91 kg) (four pigs per group) were stressed and inoculated orally with 80 ml of emulsified proliferative ilea. Severe lesions of porcine proliferative enteritis were detected in three of the four pigs weighing 6.8 kg. Mild lesions were detected in two of the four pigs in each of the other two groups. Gross lesions consisted of reticulation of the serosa, and hyperaemia and thickening of the mucosa with either fibrin or blood clots adherent to the mucosal surface. Inflammation, numerous mitotic figures and epithelial cell proliferation were observed microscopically in the crypts. Silver stained sections revealed numerous comma-shaped organisms in the crypts of infected epithelial cells. Using this method, serial reproduction of the disease was accomplished through the passage of fresh and previously frozen inocula. The virulence of the freshly prepared inoculum increased with passage through the host, whereas the inoculum prepared from tissue that had previously been frozen showed a decrease in infectivity and virulence. These data provide strong evidence for the infectious nature of this disease.