Steroid desmolase synthesis by Eubacterium desmolans and Clostridium cadavaris.

The synthesis of a steroid desmolase was demonstrated in two obligate anaerobes: a new bacterial species, Eubacterium desmolans, isolated from cat fecal flora, and Clostridium cadavaris, recovered from sewage of New York City. The enzyme cleaves the C-17-C-20 bond of corticoids possessing hydroxyl functions at C-17 and C-21. The conversion is quantitative, provided the substrate concentration is less than 100 micrograms/ml and the organisms are in the log phase. The velocity of transformation parallels the bacterial growth curve and in the log phase is higher for E. desmolans than for C. cadavaris. In addition, both organisms synthesize a 20 beta-hydroxysteroid dehydrogenase.     

The 21-acetylation of corticosteroids by Clostridium sporogenes

A strain of Clostridium sporogenes, an anaerobic bacterium, isolated from sewage in New York City synthesizes two constitutive enzymes with action on steroid molecules: (i) an enzyme capable of selectively acetylating the 21-hydroxyl function of certain steroids and (ii) the corresponding esterase. Under our experimental conditions the enzymes have a strict structural requirement for 3-keto-4-ene and C-20-keto or 20 alpha-hydroxyl group and convert their respective substrates to a mixture of free and acetylated products.     

Steroid desmolase synthesis by Eubacterium desmolans and Clostridium cadavaris

The synthesis of a steroid desmolase was demonstrated in two obligate anaerobes: a new bacterial species, Eubacterium desmolans, isolated from cat fecal flora, and Clostridium cadavaris, recovered from sewage of New York City. The enzyme cleaves the C-17-C-20 bond of corticoids possessing hydroxyl functions at C-17 and C-21. The conversion is quantitative, provided the substrate concentration is less than 100 micrograms/ml and the organisms are in the log phase. The velocity of transformation parallels the bacterial growth curve and in the log phase is higher for E. desmolans than for C. cadavaris. In addition, both organisms synthesize a 20 beta-hydroxysteroid dehydrogenase.     

A Luminex Assay Detects Amyloid β Oligomers in Alzheimer’s Disease Cerebrospinal Fluid

Amyloid beta (aβ) protein assembles into larger protein aggregates during the pathogenesis of Alzheimer’s disease (AD) and there is increasing evidence that soluble aβ oligomers are a critical pathologic species. Diagnostic evaluations rely on the measurement of increased tau and decreased aβ42 in the cerebrospinal fluid (CSF) from AD patients and evidence for oligomeric aβ in patient CSF is conflicting. In this study, we have adapted a monoclonal single antibody sandwich ELISA assay to a Luminex platform and found that this assay can detect oligomerized aβ42 and sAPPα fragments. We evaluated oligomeric aβ reactivity in 20 patients with AD relative to 19 age matched controls and compared these values with a commercially available Alzbio3 kit that detects tau, phosphorylated tau and aβ42 on the same diagnostic platform. We found that CSF samples of patients with AD had elevated aβ oligomers compared to control subjects (p < 0.05) and the ratio of aβ oligomers to aβ42 was also significantly elevated (p < 0.0001). Further research to develop high sensitivity analytical platforms and rigorous methods of developing stable assay standards will be needed before the analysis of oligomeric aβ becomes a routine diagnostic assay for the evaluation of late onset AD patients.