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Growth of Shigella spp. in the presence of the bile salt deoxycholate or chenodeoxycholate enhanced the bacterial invasion of HeLa cells. Growth in the presence of other structurally similar bile salts or detergents had little or no effect. Deoxycholate-enhanced invasion was not observed when bacteria were exposed to deoxycholate at low temperatures or when chloramphenicol was added to the growth medium, indicating that bacterial growth and protein synthesis are required. Increased invasion is associated with the presence of an intact Shigella virulence plasmid and is correlated with increased secretion of a set of proteins, including the Ipa proteins, to the outer membrane and into the growth medium. The increased invasion induced by the bile salts appears to be due to increased adherence. The enhanced adherence was specific to Shigella spp., since the enteroinvasive Escherichia coli strains tested did not exhibit the effect in response to growth in bile salts.

Systemic and gastrointestinal infection can be established in infant mice after intragastric challenge with Candida albicans. Differences in virulence of the six strains tested were noted. As early as 3 h after infection, some but not all livers, spleens, and kidneys contained C. albicans, but the peak number of colonyforming units in these organs was seen at 6 h. The early colonization of the organs could not be attributed to aspiration of the inoculum since about 90% of lungs and livers tested yielded no colony-forming units at 10 to 15 min postinfection. In animals with systemic infections, lungs, livers, kidneys, and spleens showed similar numbers of colony-forming units within the organs during the first 6 h postinfection, and then the number declined progressively up to 72 h. The gastrointestinal tract was colonized throughout a 20-day period of study. Counts made at intervals beyond day 1 yielded between 105 and 106 colony-forming units in the stomach, ileum, and cecum. Preparatory techniques for scanning electron microscopy preserved the yeast, intestinal mucus layer, and epithelial surface and made it possible to visualize the association between the pathogen and host tissues within the digestive tract. Generalized systemic infections produced by Candida albicans have increased in importance

1. Urinary excretion of 3-methylhistidine and creatinine have been measured in normal male and female humans ranging in age from pre-term neonates to 68 years to assess changes in the rate of muscle protein degradation and in muscle mass. 2. The 3-methylhistidine excretion by six adult men was measured before and after subjects were transferred to meat-free diets. It was established that a meat-free diet should be eaten for a minimum of 3 days before urine collection to eliminate exogenous sources of 3-methylhistidine. 3. The 3-methylhistidine/creatinine excretion ratio declined about twofold between normal full-term birth and maturity. The ratio in pre-term neonates was higher than for full-term neonates. 4. The variability of 3-methylhistidine/creatinine ratios between individual untime urine samples within a subject is similar to the variability between different subjects with total daily collections. 5. The 3-methylhistidine content of human muscle averaged 3.63 +/- 0.06 micromol/g for subjects aged between 4 and 65 years with protein accounting for 20.4 +/- 0.8% of muscle weight. These values are used to relate 3-methylhistidine excretion to muscle protein degradation. 6. It is concluded that control groups must be matched by age and sex to the group being examined. Where creatinine excretion is not perturbed it can be used as a reference base for comparisons of 3-methylhistidine excretion to indicate the average fractional degradation rates of muscle protein.

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Two distinct spore appendage types of Clostridium bijermentans, a pinlike appendage and a tubular appendage, were studied by electron microscopy. The pinlike appendage is characterized by a shaft, about 100 A in diameter, which has a lobed caplike structure. The tubular appendage, 500 to 600 A in diameter, is characterized by a hirsute region consisting of small filaments or fibrils. Gross morphology and ultrastructural features of both types are described. Recently, we reported the occurrence of four distinct spore appendage types among 12 strains of Clostridium bifermentans examined (9). In that report, we characterized two of the appendage types, one a smooth tubular appendage (strain 9-SDH) and the other a featherlike appendage (strain 1A-SDH). In the present report, we characterize the remaining two appendage types, a pinlike appendage (strain U-11) and a hirsute tubular appendage (strain FDA-1). In addition, some ultrastructural features of the previously reported smooth tubular appendage of strain 9-SDH are described. MATERIALS AND METHODS The experimental approach and procedures used in the present investigation were identical with those detailed in a previous report (9), and thus only an abbreviated account of these methods is given here. Three strains of C. bifermenttanis were used. Strains U-li and FDA-i were received from Stanley M. Harmon, Food and Drug Administration,

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Four distinct spore appendage types were detected in an electron microscope survey of 12 strains of Clostridium bifermentans. A smooth tubular appendage and a feather-like appendage are described in detail. In addition, hirsute tubular appendages and small pin-like appendages are depicted. Spores of four strains apparently lack appendages.