Loop-mediated isothermal amplification for paratyphoid fever - a proof-of-principle analysis.

In-house loop-mediated isothermal amplification (LAMP) procedures for the detection of paratyphoid fever-associated bacteria on serovar level were evaluated. Therefore, LAMP primers for Salmonella genus, for two LAMP schemes for S. Paratyphi A, for S. Paratyphi B and for S. Paratyphi C were tested with DNA from culture isolates from strain collections and spiked blood cultures against published PCR protocols targeting the same micro-organisms. Sensitivity and specificity for DNA from culture isolates verified by LAMP ranged from 80·0 to 100·0% and 96·1 to 100·0% vs 65 to 100% and 98·7 to 100% for the PCR approaches. For the spiked blood culture materials, sensitivity and specificity for LAMP ranged from 87·5 to 100·0% and 96·7 to 100·0% vs from 60 to 100% and 98·2 to 100% for PCR. In conclusion, LAMP for paratyphoid fever shows comparable performance characteristics as PCR. Due to its easy application, the procedure is well suited for surveillance purposes in resource-limited settings. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of easy-to-apply, point-of-care-testing-like loop-mediated isothermal amplification (LAMP) for the diagnosis of paratyphoid fever is evaluated. This approach can contribute to low-threshold availability of surveillance options for resource limited settings. Easy-to-teach and easy-to-apply LAMP schemes with similar performance characteristics as PCR are provided. The described test evaluation is of particular use for surveillance and public health experts.

Geranylgeranyl diphosphate synthase: an emerging therapeutic target.

Proteins modified post-translationally by geranylgeranylation have been implicated in numerous cellular processes related to human disease. In recent years, the study of protein geranylgeranylation has advanced tremendously in both cellular and animal models. The advances in our understanding of the biological roles of geranylgeranylated proteins have been paralleled by advances in the medicinal chemistry of geranylgeranylation inhibitors such as those that target geranylgeranyl transferases I and II and geranylgeranyl diphosphate synthase (GGDPS). Although these findings provide the rationale for further development of geranylgeranylation as a therapeutic target, more advanced studies on the efficacy of this approach in various disease models will be required to support translation to clinical studies. This article attempts to describe the advances in (and the challenges of) validation of GGDPS as a novel therapeutic target and assesses the advantages of targeting GGDPS relative to other enzymes involved in geranylgeranylation.

2-(Acyloxy)ethylphosphonate analogues of prenyl pyrophosphates: synthesis and biological characterization.

2-(Acyloxy)ethylphosphonate analogues of geranyl, farnesyl, and geranylgeranyl pyrophosphate have been prepared. Horner-Wadsworth-Emmons condensation of different terpene aldehydes with an unsymmetrical bisphosphonate was the key step in syntheses of the phosphonates bearing alpha,beta-unsaturated acyloxy groups. After preparation of the respective phosphonic acids through reaction with TMSBr, both acids and esters were tested for their effects on DNA synthesis in human-derived myeloid and lymphoid leukemia cell lines. The phosphonate esters varied substantially in their ability to impair proliferation of the different cell lines, but testing against one possible target, farnesyl protein transferase (FPTase), revealed little impact at concentrations ranging up to 10 microM. Because the corresponding 2,3-dihydro compounds showed similar biological activity, conjugate addition would not appear to be involved in the toxicity.

Synthesis of phosphonate derivatives of uridine, cytidine, and cytosine arabinoside.

The vinyl phosphonate derivatives of uridine, cytidine, and cytosine arabinoside (ara-C) have been prepared through oxidation of appropriately protected nucleosides to the 5' aldehydes and Wittig condensation with [(diethoxyphosphinyl)methylidine]triphenylphosphorane. Dihydroxylation of these vinyl phosphonates with an AD-mix reagent generated the new 5',6'-dihydroxy-6'-phosphonates. After hydrolysis of the phosphonate esters and the various protecting groups, the six phosphonic acids were tested for their ability to serve as substrates for the enzyme nucleotide monophosphate kinase and for their toxicity to K562 cells.

Engineering novel cell surface receptors for virus-mediated gene transfer.

The absence of viral receptors is a major barrier to efficient gene transfer in many cells. To overcome this barrier, we developed an artificial receptor based on expression of a novel sugar. We fed cells an unnatural monosaccharide, a modified mannosamine that replaced the acetyl group with a levulinate group (ManLev). ManLev was metabolized and incorporated into cell-surface glycoconjugates. The synthetic sugar decorated the cell surface with a unique ketone group that served as a foundation on which we built an adenovirus receptor by covalently binding biotin hydrazide to the ketone. The artificial receptor enhanced adenoviral vector binding and gene transfer to cells that are relatively resistant to adenovirus infection. These data are the first to suggest the feasibility of a strategy that improves the efficiency of gene transfer by using the biosynthetic machinery of the cell to engineer novel sugars on the cell surface.

Phosphonate and bisphosphonate analogues of farnesyl pyrophosphate as potential inhibitors of farnesyl protein transferase.

Several phosphonate and bisphosphonate analogues of farnesyl pyrophosphate have been prepared for an examination of their ability to inhibit farnesyl protein transferase (FPTase). A Horner-Wadsworth-Emmons condensation of farnesal or geranial with tetraethyl methylenediphosphonate gave the desired vinyl phosphonates, while alkylation of the dimethyl methylphosphonate anion with a terpenoid bromide gave the corresponding saturated phosphonates. Alkylation of tetraethyl methylenediphosphonate with farnesyl bromide gave the expected alkyl bisphosphonate, which was converted to its alpha, beta-unsaturated derivative by preparation of the phenyl selenide, oxidation to the selenoxide, and elimination. In a similar fashion, triethyl phosphonoacetate was converted to a farnesyl pyrophosphate analogue by reaction with farnesyl bromide. After preparation of the respective acids, each compound was tested for inhibition of FPTase at concentrations ranging up to 10 microM. The effect of these compounds on FPTase activity varied substantially, ranging from depressed to surprisingly enhanced enzymatic activity.

Stereochemistry-dependent inhibition of RAS farnesylation by farnesyl phosphonic acids.

This investigation compares the effects of three farnesyl pyrophosphate analogs on selected aspects of isoprenoid metabolism. E,E-alpha-Hydroxyfarnesylphosphonate was prepared by an improved variation on a literature synthesis, which also gave access to the new Z,E-alpha-hydroxyfarnesyl- and alpha-hydroxygeranylphosphonates. A striking find is that only E,E-alpha-hydroxyfarnesylphosphonate induces alteration of RAS processing in intact human-derived leukemia cells and inhibits farnesyl protein transferase in enzyme assays, while the Z,E-alpha-farnesyl- and geranylphosphonates are inactive. The inhibitory activity of E,E-alpha-hydroxyfarnesylphosphonate is greater in enzyme than intact cell assays. This active compound does not significantly inhibit geranylgeranyl protein transferase I or squalene synthase, nor does it diminish cholesterol synthesis. These results indicate that the length of the terpenoid chain and olefin stereochemistry allow selective inhibition of critical enzymes of terpenoid metabolism. Discrimination was observed between inhibition of farnesyl protein transferase and squalene synthase by E,E-alpha-hydroxyfarnesylphosphonate, even though both enzymes utilize farnesyl pyrophosphate as their natural substrate.

(2'S,3'S,4'R)-5'-O-benzoyl-3'-deoxy-3' beta-diethylphosphono-2'-O-tert-butyldimethylsilyluridine.

3'-Hydroxy-3'-diethylphosphononucleosides readily undergo radical deoxygenation under modified Barton conditions to give two diastereomers of the parent diethyl phosphonate. However, the stereochemistry of the diastereomers is difficult to establish by spectral means. When the major product of one such reaction was obtained in crystalline form, a single crystal diffraction analysis was conducted on that diastereomer, the title compound, C26H39N2O9PSi.

Cyclic (1R,3R)-1,3-dimethyltrimethylene [(5R)-2-hydroxy-5-methyl-5-(2- methyl-1,3-dioxolan-2-yl)-1-cyclohexen-1-yl]-phosphonate, a stable enol.

The title compound, C16H27O6P, was obtained from the rearrangement of the corresponding vinyl phosphate. 31P NMR experiments in solution have shown that this compound equilibrates to a mixture of three isomers in nearly equal proportions. In the crystalline state a single isomer is found which diffraction analysis identified as the enol form of the beta-keto phosphonate having R stereochemistry at atom C(8).

(1 beta, 5 alpha, 6 beta)-10,10- (1,2-ethylenedioxy)-1,5-dimethylbicyclo[4.4.0]decan-4-one.

The title compound (1) [alternative name: 5,8a-dimethyl(decahydronaphthalene)-1-spiro-2'-(1',3'-dioxolan+ ++)-6-one, C14H22O3] was obtained as the major product upon Pd/CaCO3-catalyzed hydrogenation of the corresponding enone (2). The analysis of the crystal structure of (1) has established that the monoacetal is cis-fused and that both rings adopt nearly perfect chair forms. The C(5) methyl group is in an alpha position, resulting directly from syn-hydrogenation of the enone. While there are two possible chair-chair conformations for cis-decalins, the title compound crystallized in the conformation which places the C(5) methyl group in an equatorial position.

Structure of a modified nucleoside, 3' alpha-diethylphosphono-3' beta-hydroxy-5'-O-tritylthymidine.

The modified nucleoside of the title was synthesized by nucleophilic addition of lithium diethyl phosphite to the corresponding 3'-keto nucleoside under basic conditions. C--P bond formation resulted from attack on the alpha face, trans to C(5') and the thymine ring. One molecule of EtOH crystallized with the nucleoside (C33H37N2O8P.-C2H6O). Intermolecular hydrogen bonds were observed between the O atom of the alcohol and the O(3')hydroxyl H atom, and between the phosphoryl O atom, O(5), and the N(3) H atom of the thymine ring.

Vidalols A and B, new anti-inflammatory bromophenols from the Caribbean marine red alga Vidalia obtusaloba.

Chemical studies of the Caribbean red alga Vidalia obtusaloba have resulted in the isolation of two new bromophenolic metabolites, vidalols A and B (1, 2). The new compounds were discovered as part of an organized effort to isolate new naturally-occurring anti-inflammatory agents with a focus upon those which may function through the inhibition of phospholipase A2.

Isolation, growth characteristics, and long-term storage of fungi cultivated by attine ants.

Seven pure-culture strains of fungi cultivated by attine ants (ant-garden fungi) were isolated from locally maintained leaf-cutting ant colonies. An ant-garden fungus strain obtained from an Atta cephalotes colony, when offered to ants of the colony from which the fungus was isolated, was accepted as their own. Young fungus cultures were harvested and incorporated into the fungus garden, and cultures of intermediate age were used to begin a new fungus garden; old cultures were simply harvested. To facilitate further research on this fungus, growth characteristics of the different isolates were studied under a variety of conditions. They grew better at 24 degrees C than at 30 degrees C, and growth did not occur at an incubation temperature of 37 degrees C. In a broth culture medium, growth was enhanced by aeration of the culture and by addition of yeast extract, olive oil, sesame oil, peanut oil, soybean oil, corn oil, sunflower oil, cottonseed oil, walnut oil, safflower oil, or mineral oil. Glycerol did not noticeably affect growth, but Tween 80 inhibited growth. These fungi were extremely sensitive to cycloheximide, growth being totally inhibited at cycloheximide concentrations ranging from 0.4 to 4.0 mug/ml. To date, the ant-garden fungus isolates have remained viable in long-term mineral oil-overlay storage cultures for up to 4 years.

Comparative deterrency of two terpenoids to two genera of attine ants.

Caryophyllene and caryophyllene epoxide are two terpenoids found in neotropical plants and known to be deterrent to leafcutter ants. To estimate the variation in deterrent activity of these compounds toward the generaAtta andAcromyrmex, behavioral bioassays were conducted over a range of concentrations. The responses of four captive colonies ofAtta cephalotes and two captive colonies ofAcromyrmex octospinosus, all from a single locality in Costa Rica, were studied. Although specific patterns of deterrency differed in the two genera, in both cases caryophyllene epoxide concentrations of 0.70 mg/g or greater, and caryophyllene concentrations of 7.0 mg/g or greater, significantly deterred the harvest of potential substrates. Individual colonies within each genus did not differ significantly in their responses to caryophyllene epoxide. The mean response of the two genera to caryophyllene epoxide differed significantly, but responses to caryophyllene did not.Acromyrmex octospinosus was more sensitive to low concentrations and less sensitive to high concentrations of caryophyllene epoxide than wasAtta cephalotes.

Toxicity of terpenoid deterrents to the leafcutting antAtta cephalotes and its mutualistic fungus.

Four natural products, of varying activity as deterrents of leafcutter attack, were tested for their effects on ant survival and on the growth of the mutualistic attine fungus. The substances were incorporated into an artificial liquid diet for bioassays on the ants or included in an agar culture medium for fungus growth-inhibition studies. Three of the four compounds exhibited deleterious effects on either adult leafcutting ants or their mutualistic fungus, and there appeared to be some correlation between deterrency and activity in these toxicity assays. The implications of these findings for leafcutting ant foraging patterns are discussed.

Nerol: An alarm substance of the stingless bee,Trigona fulviventris (Hymenoptera: Apidae).

Bees of the genusTrigona and subgenusTrigona possess volatile materials in their mandibular glands, used as alarm substances and as marking pheromones. Heads of workers ofTrigona fulviventris were analyzed by gas chromatography-mass spectrometry. The two major volatile components were nerol (∼ 50%), and octyl caproate (∼ 20%). Relative to other substances tested at a Costa Rican nest, treatments containing 20 µg of nerol attractedT. fulviventris, depressed numbers of bees leaving the nest by about 50%, and elicited wing vibration and biting. The responses were similar to those obtained with the contents of one worker head. Attraction and biting were also seen in response to captures of colony members by assassin bugs (Apiomerus pictipes) outside a nest entrance; one bee responded in about 15% of the captures. This alarm behavior, although weak, is of interest since it was thought thatT. fulviventris was unusual for its subgenus in its lack of nest defense behaviors.

Lucibufagins: Defensive steroids from the fireflies Photinus ignitus and P. marginellus (Coleoptera: Lampyridae).

Feeding tests with thrushes (Hylocichla spp.) led to the isolation of three novel steroid pyrones from fireflies (Photinus ignitus and P. marginellus) responsible, in part at least, for the unpalatability of these insects to the birds. The term lucibufagin is coined for these steroidal pyrones. The closest known relatives of lucibufagins are the familiar cardiotonic bufadienolides, found in certain toads and plants.