Obtaining useful information from expert based sources.

Clinicians rely heavily on expert based systems-consultation with colleagues, journal reviews and textbooks, and continuing education activities-to obtain new information. The usefulness of sources such as these depends on the relevance and validity of the information and the work it takes to obtain it. Useful information can be distinguished from the useless by asking three questions: Does the information focus on an outcome that my patients care about? Is the issue common to my practice, and is the intervention feasible? If the information is true, will it require me to change my practice? If the answer to all three questions is yes, then the information is a common POEM (patient oriented evidence that matters), capable of improving the lives of your patients and must be evaluated for validity. Conclusions based on results of well designed clinical trials are more likely to be valid than those drawn from observations based on experience in clinical practice. Both members of the team, clinicians and experts, must take responsibility for their respective roles.     

Enumeration of polysaccharide-degrading Bacteroides species in human feces by using species-specific DNA probes

DNA probes that are specific for each of five predominant species of human colonic Bacteroides (B. thetaiotaomicron, B. uniformis, B. distasonis, "Bacteroides group 3452-A", and B. ovatus) were used to detect and enumerate these species in fecal samples from two adult volunteers. These five species are capable of fermenting many of the complex polysaccharides that are thought to be sources of carbon and energy for bacteria in the colon. Estimates for the concentrations of some of these species in feces have not been previously available because of the difficulties in differentiating colonic Bacteroides spp. by conventional biochemical tests. Our results indicate that all the species except B. ovatus were present in high numbers (greater than 10(9)/g [dry weight]) in the feces of both volunteers. However, the concentrations of the more versatile polysaccharide-degrading species within this group of organisms (7.6 X 10(9) to 12.0 X 10(9)/g [dry weight] for B. thetaiotaomicron; 2.9 X 10(9) to 6.3 X 10(9)/g [dry weight] for "Bacteroides group 3452-A") did not differ significantly from the concentrations of less versatile polysaccharide-degrading species (1.2 X 10(10) to 2.0 X 10(10)/g [dry weight] for B. uniformis; 5.8 X 10(9) to 8.4 X 10(9)/g [dry weight] for B. distasonis). B. ovatus was not detectable by our method. Since our lower limit of detection is approximately 1 X 10(9) to 2 X 10(9)/g (dry weight) of feces, this is consistent with earlier estimates that indicated that the concentration of B. ovatus in feces is near or below this value.(ABSTRACT TRUNCATED AT 250 WORDS)     

Changes in Colonic Bile Acid Composition following Fecal Microbiota Transplantation Are Sufficient to Control Clostridium difficile Germination and Growth

Fecal microbiota transplantation (FMT) is a highly effective therapy for recurrent Clostridium difficile infection (R-CDI), but its mechanisms remain poorly understood. Emerging evidence suggests that gut bile acids have significant influence on the physiology of C. difficile, and therefore on patient susceptibility to recurrent infection. We analyzed spore germination of 10 clinical C. difficile isolates exposed to combinations of bile acids present in patient feces before and after FMT. Bile acids at concentrations found in patients’ feces prior to FMT induced germination of C. difficile, although with variable potency across different strains. However, bile acids at concentrations found in patients after FMT did not induce germination and inhibited vegetative growth of all C. difficile strains. Sequencing of the newly identified germinant receptor in C. difficile, CspC, revealed a possible correspondence of variation in germination responses across isolates with mutations in this receptor. This may be related to interstrain variability in spore germination and vegetative growth in response to bile acids seen in this and other studies. These results support the idea that intra-colonic bile acids play a key mechanistic role in the success of FMT, and suggests that novel therapeutic alternatives for treatment of R-CDI may be developed by targeted manipulation of bile acid composition in the colon.     

New insights into the size and stoichiometry of the plasminogen activator inhibitor type-1.vitronectin complex

Plasminogen activator inhibitor-type 1 (PAI-1) is the primary inhibitor of endogenous plasminogen activators that generate plasmin in the vicinity of a thrombus to initiate thrombolysis, or in the pericellular region of cells to facilitate migration and/or tissue remodeling. It has been shown that the physiologically relevant form of PAI-1 is in a complex with the abundant plasma glycoprotein, vitronectin. The interaction between vitronectin and PAI-1 is important for stabilizing the inhibitor in a reactive conformation. Although the complex is clearly significant, information is vague regarding the composition of the complex and consequences of its formation on the distribution and activity of vitronectin in vivo. Most studies have assumed a 1:1 interaction between the two proteins, but this has not been demonstrated experimentally and is a matter of some controversy since more than one PAI-1-binding site has been proposed within the sequence of vitronectin. To address this issue, competition studies using monoclonal antibodies specific for separate epitopes confirmed that the two distinct PAI-1-binding sites present on vitronectin can be occupied simultaneously. Analytical ultracentrifugation was used also for a rigorous analysis of the composition and sizes of complexes formed from purified vitronectin and PAI-1. The predominant associating species observed was high in molecular weight (M(r) approximately 320,000), demonstrating that self-association of vitronectin occurs upon interaction with PAI-1. Moreover, the size of this higher order complex indicates that two molecules of PAI-1 bind per vitronectin molecule. Binding of PAI-1 to vitronectin and association into higher order complexes is proposed to facilitate interaction with macromolecules on surfaces.     

Role of osteoblast suppression in multiple myeloma

Multiple myeloma is the most common form of plasma cell dyscrasia and virtually all cases of myeloma exhibit osteolytic lesions, which result in bone pain, pathological fractures, spinal cord compression, and hypercalcaemia. Malignant plasma cells disrupt the delicate balance between bone formation and bone resorption, which ultimately leads to the debilitating osteolytic lesions. This review focuses principally on mechanisms of osteoblast inhibition by malignant plasma cells with emphasis placed on our experimental findings, which support a model for abnormal Wnt signaling in osteoblast suppression. We describe how excessive amounts of soluble Wnt inhibitors secreted by malignant plasma cells in multiple myeloma could promote osteolytic lesions, tumor growth, suppress hematopoiesis, prevent proper engraftment, and expansion of transplanted stem cells. Finally, we detail current therapies shown to disrupt the interaction between the myeloma cell and the microenvironment, leading to activation of osteoblasts.     

Inhibition of spontaneous mutagenesis by vanillin and cinnamaldehyde in Escherichia coli: Dependence on recombinational repair

Vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutagens that effectively inhibit both induced and spontaneous mutations. We have shown previously that VAN and CIN reduced the spontaneous mutant frequency in Salmonella TA104 (hisG428, rfa, ΔuvrB, pKM101) by approximately 50% and that both compounds significantly reduced mutations at GC sites but not at AT sites. Previous studies have suggested that VAN and CIN may reduce mutations in bacterial model systems by modulating DNA repair pathways, particularly by enhancing recombinational repair. To further explore the basis for inhibition of spontaneous mutation by VAN and CIN, we have determined the effects of these compounds on survival and mutant frequency in five Escherichia coli strains derived from the wild-type strain NR9102 with different DNA repair backgrounds. At nontoxic doses, both VAN and CIN significantly reduced mutant frequency in the wild-type strain NR9102, in the nucleotide excision repair-deficient strain NR11634 (uvrB), and in the recombination-proficient but SOS-deficient strain NR11475 (recA430). In contrast, in the recombination-deficient and SOS-deficient strain NR11317 (recA56), both VAN and CIN not only failed to inhibit the spontaneous mutant frequency but actually increased the mutant frequency. In the mismatch repair-defective strain NR9319 (mutL), only CIN was antimutagenic. Our results show that the antimutagenicity of VAN and CIN against spontaneous mutation required the RecA recombination function but was independent of the SOS and nucleotide excision repair pathways. Thus, we propose the counterintuitive notion that these antimutagens actually produce a type of DNA damage that elicits recombinational repair (but not mismatch, SOS, or nucleotide excision repair), which then repairs not only the damage induced by VAN and CIN but also other DNA damage—resulting in an antimutagenic effect on spontaneous mutation.