Degenerative changes in aortic root allografts placed in the right ventricular outflow tract of growing puppies.
Differently prepared aortic root allografts were implanted in the right ventricular outflow tract of growing puppies to determine the site of origin and progress of degenerative changes in these conduits. The three preparations assessed were as follows: group A, fresh and sterile grafts; group B, antibiotic sterilized grafts in nutrient medium; and group C, beta-propiolactone sterilized grafts. Although calcification of the aortic wall occurred in all groups, the aortic leaflets were minimally affected. A correlation between viability and lack of calcification and between viability and long-term function is emphasized. (+info)
Disinfection of upper gastrointestinal fibreoptic endoscopy equipment: an evaluation of a cetrimide chlorhexidine solution and glutaraldehyde.
There is little information available on the bacteriological contamination of upper gastrointestinal fibreoptic endoscopes during routine use and the effects of 'disinfecting solutions'. A bacteriological evaluation was therefore made of cleaning an endoscope and its ancillary equipment with (1) water, (2) an aqueous solution of 1% cetrimide with 0.1% chlorhexidine, and (3) activated aqueous 2% glutaraldehyde. All equipment, but particularly the endoscope itself, was found to be heavily contaminated after use with a wide variety of organisms of which 53% were Gram positive. Cleaning the endoscope and ancillary equipment with water and the cetrimide/chlorhexidine solution alone or in combination was inadequate to produce disinfection but immersion in glutaraldehyde for two minutes consistently produced sterile cultures with our sampling technique. A rapid and simple method for disinfection of endoscopic equipment is therefore recommended and we think this is especially suitable for busy endoscopy units. (+info)
A test for 'hygienic' hand disinfection.
A standardised test procedure is described in which finger-tips are inoculated with broth cultures of organisms (Staphylococcus aureus, Staphyloccocus saprophyticus, Escherichia coli, and Pseudomonas aeruginosa): counts are made from washings of hands after disinfection with various antiseptic-detergents, alcoholic solutions, or unmedicated soap. 70% alcohol, with or without chlorhexidine, was the most effective preparation. The two antiseptic detergents showed variable results, but against Gram-negative bacilli neither was significantly more effective than plain soap. Some tests were also made on the death rate of organisms dried on the skin without disinfection. (+info)
Autoclaving impairs the connector-tube bond of the laryngeal mask airway but not its airtightness.
The general-purpose laryngeal mask airway (LMA) is re-usable when undamaged, and cleaned and autoclaved correctly. We had found weakening of the silicone adhesive that bonds the connector of the LMA to the tube. We report that repeated autoclaving damaged the adhesive such that the connector could be rotated in the tube after the 12th autoclave cycle in almost all of the LMA tested. The damage to the adhesive did not affect the airtightness of the junction, which appears to be maintained by the material properties of the connector and tube and by the shape of the join. (+info)
Mass treatment of humans who drank unpasteurized milk from rabid cows--Massachusetts, 1996-1998.
Rabies is a viral zoonosis that is usually transmitted by the bite of an infected mammal. However, in Massachusetts, two incidents have been reported since 1996 of potential mass exposures to rabies through drinking unpasteurized milk. This report presents the investigations of these two incidents. (+info)
Growth from spores of nonproteolytic Clostridium botulinum in heat-treated vegetable juice.
Unheated spores of nonproteolytic Clostridium botulinum were able to lead to growth in sterile deoxygenated turnip, spring green, helda bean, broccoli, or potato juice, although the probability of growth was low and the time to growth was longer than the time to growth in culture media. With all five vegetable juices tested, the probability of growth increased when spores were inoculated into the juice and then heated for 2 min in a water bath at 80 degrees C. The probability of growth was greater in bean or broccoli juice than in culture media following 10 min of heat treatment in these media. Growth was prevented by heat treatment of spores in vegetable juices or culture media at 80 degrees C for 100 min. We show for the first time that adding heat-treated vegetable juice to culture media can increase the number of heat-damaged spores of C. botulinum that can lead to colony formation. (+info)
Use of a whole blood assay to evaluate in vitro T cell responses to new leprosy skin test antigens in leprosy patients and healthy subjects.
Development of an immunological tool to detect infection with Mycobacterium leprae would greatly benefit leprosy control programmes, as demonstrated by the contribution of the tuberculin test to tuberculosis control. In a new approach to develop a 'tuberculin-like' reagent for use in leprosy, two new fractions of M. leprae depleted of cross-reactive and immunomodulatory lipids- MLSA-LAM (cytosol-derived) and MLCwA (cell wall-derived)-have been produced in a form suitable for use as skin test reagents. T cell responses (interferon-gamma (IFN-gamma) and lymphoproliferation) to these two new fractions were evaluated in a leprosy-endemic area of Nepal using a simple in vitro whole blood test. The two fractions were shown to be highly potent T cell antigens in subjects exposed to M. leprae-paucibacillary leprosy patients and household contacts. Responses to the fractions decreased towards the lepromatous pole of leprosy. Endemic control subjects also showed high responses to the fractions, indicating high exposure to M. leprae, or cross-reactive mycobacterial antigens, in this Nepali population. The new fractions, depleted of lipids and lipoarabinomannan (LAM) gave enhanced responses compared with a standard M. leprae sonicate. The cell wall fraction appeared a more potent antigen than the cytosol fraction, which may be due to the predominance of the 65-kD GroEL antigen in the cell wall. The whole blood assay proved a robust field tool and a useful way of evaluating such reagents prior to clinical trials. (+info)
Lethality of a heat- and phosphate-catalyzed glucose by-product to Escherichia coli O157:H7 and partial protection conferred by the rpoS regulon.
A by-product of glucose produced during sterilization (121 degrees C, 15 lb/in2, 15 min) at neutral pH and in the presence of phosphate (i.e., phosphate-buffered saline) was bactericidal to Escherichia coli O157:H7 (ATCC 43895). Other six-carbon (fructose and galactose) and five-carbon (arabinose, ribose, and xylose) reducing sugars also produced a toxic by-product under the same conditions. Fructose and the five-carbon sugars yielded the most bactericidal activity. Glucose concentrations of 1% (wt/vol) resulted in a 99.9% decline in the CFU of stationary-phase cells per milliliter in 2 days at 25 degrees C. An rpoS mutant (pRR10::rpoS) of strain 43895 (FRIK 816-3) was significantly (P < 0.001) more sensitive to the glucose-phosphate by-product than the parent strain, as glucose concentrations from 0.05 to 0.25% resulted in a 2- to 3-log10 reduction in CFU per milliliter in 2 days at 25 degrees C. Likewise, log-phase cells of the wild-type strain, 43895, were significantly more sensitive (P < 0.001) to the glucose-phosphate by-product than were stationary-phase cells, which is consistent with the stability of rpoS and the regulation of rpoS-regulated genes. The bactericidal effect of the glucose-phosphate by-product was reduced when strains ATCC 43895 and FRIK 816-3 were incubated at a low temperature (4 degrees C). Also, growth in glucose-free medium (i.e., nutrient broth) did not alleviate the sensitivity to the glucose-phosphate by-product and excludes the possibility of substrate-accelerated death as the cause of the bactericidal effect observed. The glucose-phosphate by-product was also bactericidal to Salmonella typhimurium, Shigella dysenteriae, and a Klebsiella sp. Attempts to identify the glucose-phosphate by-product were unsuccessful. These studies demonstrate the production of a glucose-phosphate by-product bactericidal to E. coli O157:H7 and the protective effects afforded by rpoS-regulated gene products. Additionally, the detection of sublethally injured bacteria may be compromised by the presence of this by-product in recovery media. (+info)