Second-generation aryl isonitrile compounds targeting multidrug-resistant Staphylococcus aureus

Antibiotic resistance remains a major global public health threat that requires sustained discovery of novel antibacterial agents with unexploited scaffolds. Structure-activity relationship of the first-generation aryl isonitrile compounds we synthesized led to an initial lead molecule that informed the synthesis of a second-generation of aryl isonitriles. From this new series of 20 compounds, three analogues inhibited growth of methicillin-resistant Staphylococcus aureus (MRSA) (from 1 to 4?µM) and were safe to human keratinocytes. Compound 19, with an additional isonitrile group exhibited improved activity against MRSA compared to the first-generation lead compound. This compound emerged as a candidate worthy of further investigation and further reinforced the importance of the isonitrile functionality in the compounds’ anti-MRSA activity. In a murine skin wound model, 19 significantly reduced the burden of MRSA, similar to the antibiotic fusidic acid. In summary, 19 was identified as a new lead aryl isonitrile compound effective against MRSA.     

The influence of medication on salivary flow of the elderly: preliminary study

doi:10.1111/j.1741‐2358.2009.00326.x
The influence of medication on salivary flow of the elderly: preliminary study Objective: This study was to evaluate the influence of medications on unstimulated and stimulated salivary flow in elderly men and women. Background: Several diseases and conditions are associated with decreasing salivary flow. Medications can be risk factors for hyposalivation due to the effect particular drug categories. Methods: Seventy‐five elderly of both gender (sixty years old or over) from the Geriatric Dental Clinic at the Federal Fluminense University Dental School, were interviewed about their health status and chronic use of medication. After the interview, unstimulated and stimulated saliva were collected from each subject. The collection time was five minutes, and the flow rate was calculated as ml/min. Results: The mean unstimulated salivary flow was 0.25 ml/min for women and 0.30 ml/min for men, while the mean for stimulated salivary flow was 1.23 ml/min for women and 1.31 ml/min for men, without both differences being non‐significant (p > 0.05). The difference between the mean production of unstimulated and stimulated salivary flow was statistically significant, regardless of gender (p < 0.01). A significant reduction of stimulated salivary flow was observed with the usage of cardiovascular agents (p < 0.05). Conclusion: Drugs used in cardiovascular disease influence the flow of stimulated saliva.     

Animated documentation of the filaria dance sign (FDS) in bancroftian filariasis

BACKGROUND: Ultrasonography is able to detect adult Wuchereria bancrofti worms in scrotal lymphatic vessels of infected men on account of the characteristic pattern of adult worm movements, known as the filarial dance sign. Furthermore, the technique is able to delineate associated pathology, such as hydrocoele and lymphoedema, which can be diagnosed in early stages. Ultrasonography is also useful in the assessment of macrofilaricidal effects of antifilarial medication.The purpose of this study was to evaluate the usefulness of scrotal ultrasonography, in combination with a new method of digital documentation, in men infected with Wuchereria bancrofti. METHODS: Ultrasonography of the scrotal areas was carried out in 33 male patients from an endemic area in Ghana using a hand-carried ultrasound system and a linear array transducer at 7.5 MHz. Wuchereria bancrofti infection was also assessed by quantification of night blood microfilaraemia and semi-quantitative detection of circulating filarial antigen. Ultrasound findings were documented by print outs and by Digital Video sequences directly exported from the ultrasound machine which were edited in Final Cut Pro 3ledR; and exported, using QuickTimecircledR; Pro, as MPEG-1 video. RESULTS: Worm nests, i.e. dilated lymphatic vessels with the characteristic movement patterns of worms, were found in all patients, and typical examples of larger as well as smaller nests are presented through MPEG-1 video in b- and m-modes as well as Colour Doppler and Pulse Wave Doppler images. CONCLUSION: In this study, the filarial dance sign is being made available on the Internet to readers through MPEG-1 video. This method allows for demonstration of movement patterns rather than static images. In addition, the pathologic ultrasonographic signs of filariasis can be rapidly relayed over great distances and may be helpful to other investigators or clinicians in the diagnosis of patients infected with Wuchereria bancrofti.     

Interactions between the endocrine and immune systems in locusts

Abstract. The prophenoloxidase cascade in the haemolymph of mature adult Locusta migratoria migratorioides (R & F) is activated in response to injection of laminarin, a β‐1,3 glucan. Co‐injection of adipokinetic hormone‐I (Lom‐AKH‐I) and laminarin prolongs the activation of the enzyme in a dose‐dependent manner. However, injections of bacterial lipopolysaccharide (LPS) do not activate prophenoloxidase unless AKH is co‐injected, when there is a dose‐dependent increase in the level of phenoloxidase that persists in the haemolymph for several hours. Even when AKH is co‐injected, the highest levels of phenoloxidase activity are always greater after injection of laminarin than after LPS, and these two immunogens must activate the prophenoloxidase cascade by quite distinct pathways. In the present study, interactions between the endocrine and immune systems were examined with respect to activation of prophenoloxidase and the formation of nodules: injection of LPS induces nodule formation in adult locusts. With LPS from Pseudomonas aeruginosa, nodules form exclusively in dense accumulations in the anterior portion of the abdomen on either side of the dorsal blood vessel associated with the dorsal diaphragm. However, with LPS from Escherichia coli, fewer nodules are formed but with a similar distribution, except that occasionally some nodules are aligned additionally on either side of the ventral nerve cord. Co‐injection of Lom‐AKH‐I with LPS from either bacteria stimulates greater numbers of nodules to be formed. This effect of coinjection of AKH on nodule formation is seen at low doses of hormone with only 0.3 or 0.4 pmol of Lom‐AKH‐1, respectively, increasing the number of nodules by 50%. Injections of octopamine or 5‐hydroxytryptamine do not mimic either of the actions of Lom‐AKH‐I described here. Co‐injection of an angiotensin‐converting enzyme inhibitor, captopril, reduces nodule formation in response to injections of LPS but has no effect on the activation of phenoloxidase. Co‐injection of an inhibitor of eicosanoid synthesis, dexamethasone, with LPS influences nodule formation (with or without AKH) in different ways according to the dose of dexamethasone used, but does not affect activation of prophenoloxidase. Eicosanoid synthesis is important for nodule formation, but not for the activation of the prophenoloxidase cascade in locust haemolymph.     

Investigation of aryl isonitrile compounds with potent,broad-spectrum antifungal activity

Invasive fungal infections present a formidable global public health challenge due to the limited number of approved antifungal agents and the emergence of resistance to the frontline treatment options, such as fluconazole. Three fungal pathogens of significant concern are Candida, Cryptococcus, and Aspergillus given their propensity to cause opportunistic infections in immunocompromised individuals. New antifungal agents composed of unique chemical scaffolds are needed to address this public health challenge. The present study examines the structure-activity relationship of a set of aryl isonitrile compounds that possess broad-spectrum antifungal activity primarily against species of Candida and Cryptococcus. The most potent derivatives are capable of inhibiting growth of these key pathogens at concentrations as low as 0.5 µM. Remarkably, the most active compounds exhibit an excellent safety profile and are non-toxic to mammalian cells even at concentrations up to 256 µM. The present study lays the foundation for further investigation of aryl isonitrile compounds as a new class of antifungal agents.     

Omphalocarpoidone,a new lanostane-type furano-spiro-γ-lactone from the wood of Tridesmostemon omphalocarpoides Engl. (Sapotaceae)

Phytochemical studies of the wood and the stem bark of Tridesmostemon omphalocarpoides Engl. (Sapotaceae) led to the isolation of omphalocarpoidone (1), a new lanostane-type furano-spiro-γ-lactone together with β-amyrin acetate (2), taraxerol (3), spinasterol (4), lichexanthone (5), epi-catechin (6), spinasterol 3-O-β-d-glucopyranoside (7), tormentic acid (8), and 1,2,3,4-tetrahydronorharman-1-one (9). Their structures were established on the basis of extensive NMR studies, mass spectrometry, and by comparison of the data with those previously reported in the literature. The structure of the new secondary metabolite was later confirmed by X-ray crystallography. Except for spinasterol, the antimicrobial activities of these secondary metabolites were investigated on ten bacterial strains and the alkaloid 9 showed a significant activity against Escherichia coli with a MIC at 16 μg/mL.     

The Benefits or Otherwise of Managing Malaria Cases with or without Laboratory Diagnosis: The Experience in a District Hospital in Ghana

Background

This study was conducted at the Kintampo Municipal Hospital in Ghana to determine whether there was any benefit (or otherwise) in basing the management of cases of suspected malaria solely on laboratory confirmation (microscopy or by RDT) as compared with presumptive diagnosis.

Method

Children under five years who reported at the Out-Patient Department of the Hospital with axillary temperature ≥37.5°C or with a 48 hr history of fever were enrolled and had malaria microscopy and RDT performed. The attending clinician was blinded from laboratory results unless a request for these tests had been made earlier. Diagnosis of malaria was based on three main methods: presumptive or microscopy and/or RDT. Cost implication for adopting laboratory diagnosis or not was determined to inform malaria control programmes.

Results

In total, 936 children were enrolled in the study. Proportions of malaria diagnosed presumptively, by RDT and microscopy were 73.6% (689/936), 66.0% (618/936) and 43.2% (404/936) respectively. Over 50% (170/318) of the children who were RDT negative and 60% (321/532) who were microscopy negative were treated for malaria when presumptive diagnoses were used. Comparing the methods of diagnoses, the cost of malaria treatment could have been reduced by 24% and 46% in the RDT and microscopy groups respectively; the reduction was greater in the dry season (43% vs. 50%) compared with the wet season (20% vs. 45%) for the RDT and microscopy confirmed cases respectively.

Discussion/Conclusion

Over-diagnosis of malaria was prevalent in Kintampo during the period of the study. Though the use of RDT for diagnosis of malaria might have improved the quality of care for children, it appeared not to have a cost saving effect on the management of children with suspected malaria. Further research may be needed to confirm this.     

Case study and application of process analytical technology (PAT) towards bioprocessing: use of on-line high-performance liquid chromatography (HPLC) for making real-time pooling decisions for process chromatography

Process analytical technology (PAT) has been gaining a lot of momentum in the biopharmaceutical community due to the potential for continuous real time quality assurance resulting in improved operational control and compliance. This paper presents a PAT application for one of the most commonly used unit operation in bioprocessing, namely liquid chromatography. Feasibility of using a commercially available online-high performance liquid chromatography (HPLC) system for real-time pooling of process chromatography column is examined. Further, experimental data from the feasibility studies are modeled and predictions of the model are compared to actual experimental data. It is found that indeed for the application under consideration, the online-HPLC offers a feasible approach for analysis that can facilitate real-time decisions for column pooling based on product quality attributes. It is shown that implementing this analytical scheme allows us to meet two of the key goals that have been outlined for PAT, that is, "variability is managed by the process" and "product quality attributes can be accurately and reliably predicted over the design space established for materials used, process parameters, manufacturing, environmental, and other conditions." Finally, the implications of implementing such a PAT application in a manufacturing environment are discussed. The application presented here can be extended to other modes of process chromatography and/or HPLC analysis.     

Multiple conformations of SAM-II riboswitch detected with SAXS and NMR spectroscopy

Riboswitches are a newly discovered large family of structured functional RNA elements that specifically bind small molecule targets out of a myriad of cellular metabolites to modulate gene expression. Structural studies of ligand-bound riboswitches by X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy have provided insights into detailed RNA-ligand recognition and interactions. However, the structures of ligand-free riboswitches remain poorly characterized. In this study, we have used a variety of biochemical, biophysical and computational techniques including small-angle X-ray scattering and NMR spectroscopy to characterize the ligand-free and ligand-bound forms of SAM-II riboswitch. Our data demonstrate that the RNA adopts multiple conformations along its folding pathway and suggest that the RNA undergoes marked conformational changes upon Mg(2+) compaction and S-adenosylmethionine (SAM) metabolite binding. Further studies indicated that Mg(2+) ion is not essential for the ligand binding but can stabilize the complex by facilitating loop/stem interactions. In the presence of millimolar concentration of Mg(2+) ion, the RNA samples a more compact conformation. This conformation is near to, but distinct from, the native fold and competent to bind the metabolite. We conclude that the formation of various secondary and tertiary structural elements, including a pseudoknot, occur to sequester the putative Shine-Dalgarno sequence of the RNA only after metabolite binding.