Older adults have the highest risk of death by suicide in the United States. Improving our understanding of the factors that lead to increased risk of suicide in older adults will greatly inform our ability to prevent suicide in this high-risk group. Two studies were conducted to test the effect of perceived burdensomeness, a component of the interpersonal-psychological theory of suicide (Joiner, 2005), on suicide ideation in older adults. Further, gender was examined as a moderator of this association to determine if perceived burdensomeness exerted a greater influence on suicide ideation in males. The results of these studies suggest that perceived burdensomeness accounts for significant variance in suicide ideation, even after predictors such as depressive symptoms, hopelessness, and functional impairment are controlled. Gender did not moderate the association. The implications of these findings for treatment of older adults with suicide ideation and elevated suicide risk are discussed.
Previous investigations have shown that certain strains of lactobacilli can competitively exclude uropathogens from attaching to uroepithelial cells and from causing urinary tract infection in animals. The finding of an inhibitory effect produced by Lactobacillus casei ssp. rhamnosus GR-1 against the growth of uropathogens was investigated further using two Escherichia coli indicator strains Hu 734 and ATCC 25922. There were two phases to the inhibitor studies. The first one using an agar sandwich technique showed that the inhibitor activity was heat stable and inhibitory to the E. coli. The second phase showed that MRS broth provided optimum lactobacilli growth and inhibitor production. In addition, the inhibition was present under conditions buffering for acid and pH. The data indicated that the inhibitory effect was not due to bacteriophages or hydrogen peroxide. Strain GR-1 was found to coaggregate with E. coli ATCC 25922 in urine, a phenomenon that has not previously been reported for urogenital bacteria. An in vitro assay system was developed to study the coaggregation of various lactobacilli and uropathogens. The results demonstrated that highest coaggregation scores occurred after 4 h incubation at 37 degrees C with lactobacilli and two type-1 fimbriated E. coli strains. Of the nine lactobacilli strains tested, each was found to coaggregate with 2 or more of the 13 uropathogens. The dominance of inhibitor-producing lactobacilli on the urogenital epithelium and the ability of these organisms to interact closely with uropathogens would constitute an important host defense mechanism against infection.
Lactobacilli strains vary in their ability to interfere with colonization of uroepithelial cells by pathogenic organisms. Bacterial size, adherence capability, competitive exclusion and inhibition of pathogenic growth were examined in selected strains of lactobacilli to assess their relative importance. We tested adherence to uroepithelial cells of 34 lactobacillus isolates originating from the urogenital tract, dairy sources and chickens, and 1 lactobacillus strain isolated from a commercially available preparation. The ability to adhere differed greatly among the 34 strains, with a range of 8 to 74 bacteria per cell, and the commercial strain attached poorly with a mean of 15 bacteria per cell. Eleven strains of lactobacilli were selected and found to differ in length and width dimensions. These strains were found to exclude competitively with varying efficiency 6 strains of uropathogens from adhering to uroepithelial cells. The effective ability of Lactobacillus casei GR-1 to exclude the uropathogens confirmed previous findings and other strains (GR-2, GR-3 and A-60) gave a similar range of exclusion. The lactobacillus isolates varied greatly in their ability to inhibit the growth of 11 uropathogens under the conditions of an agar overlay inhibition assay. A combination score was allocated to each of the 11 lactobacillus strains based on size, adherence, exclusion and inhibition. Lactobacillus casei GR-1 attained the highest score while the commercial strain attained the lowest score. The results of this study identified 4 properties that should be examined to select lactobacillus strains before embarking upon bacterial interference studies to prevent urinary tract and other infections in humans.
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