Opening the black box of mixed-metal TMP metallating reagents : direct cadmation or lithium-cadmium transmetallation?

Designed to remove some of the mystery surrounding mixed-metal TMP (2,2,6,6-tetramethylpiperidide) metallating reagents, this study examines in detail "LiCd(TMP)(3)'' in its own right. Previously established as an excellent "cadmating'' (Cd-H exchange) reagent towards a wide variety of aromatic substrates, "LiCd(TMP)(3)'' has been investigated by H-1, C-13 and Cd-113 NMR studies as well as by DOSY NMR spectroscopy. This evidence puts a question mark against its ate formulation implying it exists in THF solution as two independent homometallic amides. Exploring the reactivity of "LiCd(TMP)(3)'' with anisole as a test substrate, both experimentally by NMR studies and theoretically by DFT studies suggests a two-step lithiation/transmetallation process in which the initially formed ortho-lithiated species undergoes a reaction with Cd(TMP)(2) to form new Cd-C and Li-N bonds. For completeness, the homometallic cadmium component Cd(TMP)(2) has been comprehensively characterised for the first time including a crystal structure determination revealing a near-linear N-Cd-N arrangement

Structural and magnetic diversity in alkali-metal Manganate chemistry : evaluating donor and alkali-metal effects in co-complexation processes

By exploring co-complexation reactions between the manganese alkyl Mn(CH2SiMe3)2 and the heavier alkali-metal alkyls M(CH2SiMe3) (M=Na, K) in a benzene/hexane solvent mixture and in some cases adding Lewis donors (bidentate TMEDA, 1,4-dioxane, and 1,4-diazabicyclo[2,2,2] octane (DABCO)) has produced a new family of alkali-metal tris(alkyl) manganates. The influences that the alkali metal and the donor solvent impose on the structures and magnetic properties of these ates have been assessed by a combination of X-ray, SQUID magnetization measurements, and EPR spectroscopy. These studies uncover a diverse structural chemistry ranging from discrete monomers [(TMEDA)2MMn(CH2SiMe3)3] (M=Na, 3; M=K, 4) to dimers [(KMn(CH2SiMe3)3C6H6)2] (2) and [(NaMn(CH2SiMe3)3)2(dioxane)7] (5); and to more complex supramolecular networks [(NaMn(CH2SiMe3)3)∞] (1) and [(Na2Mn2(CH2SiMe3)6(DABCO)2)∞] (7)). Interestingly, the identity of the alkali metal exerts a significant effect in the reactions of 1 and 2 with 1,4-dioxane, as 1 produces coordination adduct 5, while 2 forms heteroleptic [((dioxane)6K2Mn2(CH2SiMe3)4(O(CH2)2OCH=CH2)2)∞] (6) containing two alkoxide-vinyl anions resulting from α-metalation and ring opening of dioxane. Compounds 6 and 7, containing two spin carriers, exhibit antiferromagnetic coupling of their S=5/2 moments with varying intensity depending on the nature of the exchange pathways

Early severe inflammatory responses to uropathogenic E. coli predispose to chronic and recurrent urinary tract infection

Chronic infections are an increasing problem due to the aging population and the increase in antibiotic resistant organisms. Therefore, understanding the host-pathogen interactions that result in chronic infection is of great importance. Here, we investigate the molecular basis of chronic bacterial cystitis. We establish that introduction of uropathogenic E. coli (UPEC) into the bladders of C3H mice results in two distinct disease outcomes: resolution of acute infection or development of chronic cystitis lasting months. The incidence of chronic cystitis is both host strain and infectious dose-dependent. Further, development of chronic cystitis is preceded by biomarkers of local and systemic acute inflammation at 24 hours post-infection, including severe pyuria and bladder inflammation with mucosal injury, and a distinct serum cytokine signature consisting of elevated IL-5, IL-6, G-CSF, and the IL-8 analog KC. Mice deficient in TLR4 signaling or lymphocytes lack these innate responses and are resistant, to varying degrees, to developing chronic cystitis. Treatment of C3H mice with the glucocorticoid anti-inflammatory drug dexamethasone prior to UPEC infection also suppresses the development of chronic cystitis. Finally, individuals with a history of chronic cystitis, lasting at least 14 days, are significantly more susceptible to redeveloping severe, chronic cystitis upon bacterial challenge. Thus, we have discovered that the development of chronic cystitis in C3H mice by UPEC is facilitated by severe acute inflammatory responses early in infection, which subsequently are predisposing to recurrent cystitis, an insidious problem in women. Overall, these results have significant implications for our understanding of how early host-pathogen interactions at the mucosal surface determines the fate of disease

Pre-inverse-crowns : synthetic, structural and reactivity studies of alkali metal magnesiates primed for inverse crown formation

Two new alkali metal monoalkyl-bisamido magnesiates, the potassium compound [KMg(TMP)2nBu] and its sodium congener [NaMg(TMP) 2nBu] have been synthesised in crystalline form (TMP = 2,2,6,6-tetramethylpiperidide). Devoid of solvating ligands and possessing excellent solubility in hydrocarbon solvents, these compounds open up a new gateway for the synthesis of inverse crowns. X-ray crystallography established that [KMg(TMP)2nBu] exists in three polymorphic forms, namely a helical polymer with an infinite KNMgN chain, a hexamer with a 24-atom (KNMgN)6 ring having endo-disposed alkyl substituents, and a tetramer with a 16-atom (KNMgN)4 ring also having endo-disposed alkyl substituents. Proving their validity as pre-inverse-crowns, both magnesiates react with benzene and toluene to generate known inverse crowns in syntheses much improved from the original, supporting the idea that the metallations take place via a template effect. [KMg(TMP)2nBu] reacts with naphthalene to generate the new inverse crown [KMg(TMP)2(2-C 10H7)]6, the molecular structure of which shows a 24-atom (KNMgN)6 host ring with six naphthalene guest anions regioselectively magnesiated at the 2-position. An alternative unprecedented 1,4-dimagnesiation of naphthalene was accomplished via [NaMg(TMP) 2nBu] and its NaTMP co-complex "[NaMg(TMP) 2nBu]·NaTMP", manifested in [{Na 4Mg2(TMP)4(2,2,6-trimethyl-1,2,3,4- tetrahydropyridide)2}(1,4-C10H6)]. Adding to its novelty, this 12-atom (NaNNaNMgN)2 inverse crown structure contains two demethylated TMP ligands as well as four intact ones. Reactivity studies show that the naphthalen-ide and -di-ide inverse crowns can be regioselectively iodinated to 2-iodo and 1,4-diiodonaphthalene respectively

Efficacy of a broad host range lytic bacteriophage against E. coli adhered to urothelium

Persistent urinary tract infections (UTI) are often caused by E. coli adhered to urothelium. This type of cells is generally recognized as very tolerant to antibiotics which renders difficult the treatment of chronic UTI. This work investigates the use of lytic bacteriophages as alternative antimicrobial agents, particularly the interaction of phages with E. coli adhered to urothelium and specifically determines their efficiency against this type of cells. The bacterial adhesion to urothelium was performed varying the bacterial cell concentrations and the period and conditions (static, shaken) of adhesion. Three collection bacteriophages (T1, T4 and phiX174 like phages) were tested against clinical E. coli isolates and only one was selected for further infection experiments. Based on the lytic spectrum against clinical isolates and its ability to infect the highest number of antibiotic resistant strains, the T1-like bacteriophage was selected. This bacteriophage caused nearly a 45 % reduction of the bacterial population after 2 h of treatment. This study provides evidence that bacteriophages are effective in controlling suspended and adhered cells and therefore can be a viable alternative to antibiotics to control urothelium adhered bacteria

Bacteria-Induced Uroplakin Signaling Mediates Bladder Response to Infection

Urinary tract infections are the second most common infectious disease in humans and are predominantly caused by uropathogenic E. coli (UPEC). A majority of UPEC isolates express the type 1 pilus adhesin, FimH, and cell culture and murine studies demonstrate that FimH is involved in invasion and apoptosis of urothelial cells. FimH initiates bladder pathology by binding to the uroplakin receptor complex, but the subsequent events mediating pathogenesis have not been fully characterized. We report a hitherto undiscovered signaling role for the UPIIIa protein, the only major uroplakin with a potential cytoplasmic signaling domain, in bacterial invasion and apoptosis. In response to FimH adhesin binding, the UPIIIa cytoplasmic tail undergoes phosphorylation on a specific threonine residue by casein kinase II, followed by an elevation of intracellular calcium. Pharmacological inhibition of these signaling events abrogates bacterial invasion and urothelial apoptosis in vitro and in vivo. Our studies suggest that bacteria-induced UPIIIa signaling is a critical mediator of bladder responses to insult by uropathogenic E. coli

Secondary Chromosomal Attachment Site and Tandem Integration of the Mobilizable Salmonella Genomic Island 1

The Salmonella genomic island 1 is an integrative mobilizable element (IME) originally identified in epidemic multidrug-resistant Salmonella enterica serovar Typhimurium (S. Typhimurium) DT104. SGI1 contains a complex integron, which confers various multidrug resistance phenotypes due to its genetic plasticity. Previous studies have shown that SGI1 integrates site-specifically into the S. enterica, Escherichia coli, or Proteus mirabilis chromosome at the 3′ end of thdF gene (attB site)