Characterisation of Anopheles strains used for laboratory screening of new vector control products

BACKGROUND

Insecticides formulated into products that target Anopheles mosquitos have had an immense impact on reducing malaria cases in Africa. However, resistance to currently used insecticides is spreading rapidly and there is an urgent need for alternative public health insecticides. Potential new insecticides must be screened against a range of characterized mosquito strains to identify potential resistance liabilities. The Liverpool School of Tropical Medicine maintains three susceptible and four resistant Anopheles strains that are widely used for screening for new insecticides. The properties of these strains are described in this paper.

METHODS

WHO tube susceptibility bioassays were used for colony selection and to screen for resistance to the major classes of public health insecticides. Topical and tarsal contact bioassays were used to produce dose response curves to assess resistance intensity. Bioassays with the synergist piperonyl butoxide were also performed. Taqman™ assays were used to screen for known target site resistance alleles (kdr and ace-1). RT-qPCR was used to quantify expression of genes associated with pyrethroid resistance.

RESULTS

Pyrethroid selection pressure has maintained resistance to this class in all four resistant strains. Some carbamate and organophosphate resistance has been lost through lack of exposure to these insecticide classes. The Anopheles gambiae (sensu lato) strains, VK7 2014, Banfora M and Tiassalé 13 have higher levels of pyrethroid resistance than the An. funestus FUMOZ-R strain. Elevated expression of P450s is found in all four strains and the 1014F kdr mutation is present in all three An. gambiae strains at varying frequencies. Tarsal contact data and overexpression of CYP4G16 and SAP2 suggest penetration barriers and/or sequestration also confer resistance in Banfora M.

CONCLUSIONS

Continual selection with deltamethrin has maintained a stable pyrethroid-resistant phenotype over many generations. In conjunction with a standardized rearing regime, this ensures quality control of strains over time allowing for robust product comparison and selection of optimal products for further development. The identification of multiple mechanisms underpinning insecticide resistance highlights the importance of screening new compounds against a range of mosquito strains.

Day of surgery admission for the elective surgical in-patient: successful implementation of the Elective Surgery Programme

BACKGROUND AND AIMS

The aim of this prospective cross-sectional study was to determine the impact of (1) ring fencing in-patient general surgical beds and (2) introducing a pre-operative assessment clinic (PAC) on the day of surgery admission (DOSA) rate in a single Irish institution. The secondary aim was to analyse the impact of an increased rate of DOSA on cost efficiency and patient satisfaction.

METHODS

An 18-month period was examined following ring-fencing of elective and emergency surgical beds. A PAC was established during the study period. Prospectively collected data pertaining to all surgical admissions were retrieved using patient administration system software (Powerterm Pro, Eircom Software) and a database of performance information from Irish Public Health Services (HealthStat).

RESULTS

Ring-fencing and PAC establishment was associated with a significant increase in the overall DOSA rate from 56 to 85%, surpassing the national target rate of DOSA (75%). Data relating specifically to general surgery admissions mirrored this increase in DOSA rate from a median of 5 patients per month, before the advent of ring-fencing and PAC, to 42 patients per month (p < 0.0387). 100 patient surveys demonstrated high levels of satisfaction with DOSA, with a preference compared to admission one night pre-operatively. Cost analysis demonstrated overall savings of 340,370 Euro from this change in practice.

CONCLUSION

The present study supports the practice of DOSA through the introduction of ring-fenced surgical beds and PAC. This has been shown to improve hospital resource utilisation and streamline surgical service provision in these economically challenging times.

Three years of insecticide resistance monitoring in Anopheles gambiae in Burkina Faso: resistance on the rise?

Background and methods

A longitudinal Anopheles gambiae s.l. insecticide-resistance monitoring programme was established in four sentinel sites in Burkina Faso. For three years, between 2008 and 2010, WHO diagnostic dose assays were used to measure the prevalence of resistance to all the major classes of insecticides at the beginning and end of the malaria transmission season. Species identification and genotyping for target site mutations was also performed and the sporozoite rate in adults determined.

Results

At the onset of the study, resistance to DDT and pyrethroids was already prevalent in An. gambiae s.l. from the south-west of the country but mosquitoes from the two sites in central Burkina Faso were largely susceptible. Within three years, DDT and permethrin resistance was established in all four sites. Carbamate and organophosphate resistance remains relatively rare and largely confined to the south-western areas although a small number of bendiocarb survivors were found in all sites by the final round of monitoring. The ace-1^R target site resistance allele was present in all localities and its frequency exceeded 20% in 2010 in two of the sites. The frequency of the 1014F kdr mutation increased throughout the three years and by 2010, the frequency of 1014F in all sites combined was 0.02 in Anopheles arabiensis, 0.56 in An. gambiae M form and 0.96 in An. gambiae S form. This frequency did not differ significantly between the sites. The 1014S kdr allele was only found in An. arabiensis but its frequency increased significantly throughout the study (P = 0.0003) and in 2010 the 1014S allele frequency was 0.08 in An. arabiensis. Maximum sporozoite rates (12%) were observed in Soumousso in 2009 and the difference between sites is significant for each year.

Conclusion

Pyrethroid and DDT resistance is now established in An. gambiae s.l. throughout Burkina Faso. Results from diagnostic dose assays are highly variable within and between rounds of testing, and hence it is important that resistance monitoring is carried out on more than one occasion before decisions on insecticide procurement for vector control are made. The presence of 1014S in An. gambiae s.l., in addition to 1014F, is not unexpected given the recent report of 1014S in Benin but highlights the importance of monitoring for both mutations throughout the continent. Future research must now focus on the impact that this resistance is having on malaria control in Burkina Faso.

A rare case of Amyand's hernia presenting as an enterocutaneous fistula

The finding of the vermiform appendix in an inguinal hernia has an incidence of approximately 1%. The condition is given the eponymous name Amyand’s hernia. However in just 0.08% the condition is complicated by an acute appendicitis. The clinical presentation varies, depending on the extent of inflammation of the appendix and is most often misdiagnosed as an incarcerated inguinal hernia. As such it is rarely recognised prior to surgical exploration. We report a case of Amyand’s hernia in an 85 year old woman, which presented as a right groin enterocutaneous fistula. CT scanning illustrated a fistulous tract in the right groin, which communicated with the caecum and the peritoneal cavity. She underwent laparotomy, which revealed that the appendix appeared inflamed, lay in the inguinal canal and was the origin of the enterocutaneous communication.

Patients with ulcerative colitis responding to steroid treatment up-regulate glucocorticoid receptor levels in colorectal mucosa

BACKGROUND AND AIMS

Glucocorticosteroid treatment (GCS) is effective for attacks of ulcerative colitis (UC). However, 25-30% of patients fails to respond and may be considered steroid resistant. Glucocorticoid receptors (GR) mediate the effects of GCS. Colorectal mucosa levels of GR and NF-κB were analysed before, during and after treatment with GCS-compounds.

METHODS

Patients with moderate-severe attacks of ulcerative colitis were included. Patients undergoing colonoscopy with normal finding served as controls. GR and NF-κB levels in colorectal mucosa were analysed by Western Blotting and the DNA-binding activity of NF-κB by EMSA.

RESULTS

Twenty-eight patients and seven controls were included. Ten patients were judged clinically steroid resistant. Responders had significantly higher levels of GR in colorectal mucosa after one week of treatment than non-responders (P=0.039) and significantly higher levels of GR were found in responders in remission as compared to before treatment (P=0.013). NF-κB levels did not differ between the groups at first visit. Increasing levels were found only in responders as remission was obtained (P=0.031). EMSA detected 20% lower DNA-binding of NF-κB in responders in remission as compared to first visit (P=0.021).

CONCLUSION

GR levels increase in UC-patients responding to GCS-therapy but not in steroid resistant patients and may be the reason for the lack of steroid-efficacy. Increasing NF-κB levels were found in responders attaining remission, possibly reflecting a lower turnover. A decrease in DNA-binding of NF-κB was found in these patients, perhaps because of the increased GR levels counteracting NF-κB activity.

Combining near infrared spectroscopy and multivariate analysis as a tool to differentiate different strains ofSaccharomyces cerevisiae: a metabolomic study

Near-infrared (NIR) spectroscopy has gained wide acceptance within the food and agriculture industries as a rapid analytical tool. NIR spectroscopy offers the advantage of rapid, non-destructive analysis and routine operation is simple and opens the possibility of using spectra to obtain the 'fingerprint' of a sample. The aim of this study was to explore the potential of combining visible (VIS) and near-infrared (NIR) spectroscopy, together with multivariate analysis, in establishing the function of genes, by investigating the metabolic profiles produced by Saccharomyces cerevisiae deletion strains sourced from the EUROSCARF yeast collection. Spectra (400-2500 nm) were acquired with a FOSS NIRSystems6500 (Foss NIRSystems), in transmittance mode. Principal component analysis (PCA) and linear discriminant analysis (LDA) were used in order to visualize graphically the relative differences and similarities of yeast deletion strains. VIS and NIR spectroscopy showed great promise as a screening tool for both discriminating between yeast strains and grouping strains with deletions in genes that disturb similar metabolic pathways. These results indicate that the methods may be useful in defining the function of genes that produce no obvious phenotype.

Glucocorticoid receptor mRNA in patients with ulcerative colitis: a study of responders and nonresponders to glucocorticosteroid therapy

BACKGROUND AND AIMS

Up to 30% of patients with severe-to-moderate attacks of ulcerative colitis (UC) respond poorly to glucocorticosteroid (GCS) treatment. The reason for this unresponsiveness is unknown.

AIM

Our aim was to evaluate possible differences in glucocorticoid receptor (GR) density in peripheral leukocytes and effects of low-dose GCS treatment on GR density and on the hypothalamic-pituitary-adrenal axis in UC patients who had received high-dose GCS treatment due to a moderate or severe attack. Eleven UC patients in remission who were responders (Rs) to previous GCS treatment were compared with 10 patients who failed GCS therapy and had a colectomy (nonresponders. NRs). Ten healthy individuals served as controls.

METHODS

Quantitation of GR mRNA by a solution hybridization assay in peripheral leukocytes and a low-dose adrenocorticotropin hormone stimulation test was performed before and after low-dose dexamethasone (DEX) treatment for 14 days. The glucocorticoid-responsive gene for metallothionein IIa (MTIIa) was also analyzed by a solution hybridization assay in peripheral leukocytes.

RESULTS

Overall, basal GR mRNA levels were higher in patients than in controls (p < 0.0001). There were no significant differences between NRs and Rs. None of the groups down-regulated their GR mRNA levels in response to DEX treatment. Basal and stimulated cortisol levels decreased significantly only among NRs after DEX (p = 0.012 and 0.0093). MTIIa levels were lower in NRs as compared with Rs, both in mononuclear (p = 0.0059) and in polynuclear leukocytes (p = 0.030).

CONCLUSION

Patients with UC in remission exhibit higher levels of GR mRNA in peripheral leukocytes. We speculate that this may be secondary to an underlying up-regulation of proinflammatory factors also present in patients in clinical remission. Differences in GR mRNA levels per se thus may not be important for the ability of patients with UC to respond to GCS treatment. The hypothalamic pituitary adrenal axis was suppressed by low-dose DEX treatment only in NRs, possibly indicating that steroid-resistance is not a generalized phenomenon. Lower levels of MTIIa in NRs may indicate a diminished efficiency of GR regulation in steroid-refractory patients.

Low molecular weight heparin as adjuvant therapy in active ulcerative colitis

BACKGROUND

Heparin given intravenously has shown beneficial effects in the treatment of refractory ulcerative colitis in open trials. Low molecular weight heparin (LMWH) offers advantages in the method of administration but have not been evaluated in inflammatory bowel disease conditions.

AIM

To assess the tolerability and safety of subcutaneous self-administered LMWH in outpatients with refractory ulcerative colitis and to evaluate any potential adjuvant therapeutic effect.

PATIENTS AND METHODS

Twelve patients with mild to moderately active ulcerative colitis were included in the trial. The patients had either responded poorly to treatment with conventional therapy, including oral and/or rectal glucocorticosteroids, or had experienced a rapid relapse during or shortly after GCS therapy. Dalteparin sodium 5000 units s.c. injection was administered twice daily for 12 weeks. Patients were monitored for possible adverse events and changes in clinical symptoms, and endoscopic and histological scores were analysed. Leucocyte scanning was performed at inclusion and at the end of the study.

RESULTS

Tolerability and compliance were excellent and no serious adverse events occurred. Eleven patients improved symptomatically and six (50%) attained complete remission after 12 weeks of treatment. Endoscopic, scintigraphic and histological scores were found to be significantly improved.

CONCLUSION

Self-administered LMWH given s.c. may be a safe adjuvant therapy for patients with active, glucocorticosteroids-refractory ulcerative colitis. A controlled trial should be undertaken to confirm the positive effects found in this study.

Redox-dependent regulation of interleukin-8 by tumor necrosis factor-alpha in lung epithelial cells

Increasing evidence supports a major role for interleukin-8 (IL-8), a potent neutrophil chemoattractant, in the chronic progression of inflammatory lung diseases. The present studies were designed to characterize the molecular events involved in IL-8 induction in pulmonary epithelial cells in response to tumor necrosis factor-alpha (TNF-alpha). IL-8 induction by TNF-alpha was redox sensitive, as indicated by electron spin resonance analysis and inhibition with membrane permeable hydroxyl scavengers. Furthermore using cell transfection and mobility shift assays, it was found that transcriptional activation of the IL-8 gene required TNF-alpha-induced activation and binding of nuclear factor-kappaB (NF-kappaB)- and NF-IL-6, nuclear transcription factors to regulatory elements in the IL-8 promoter. Activation of the IL-8 promoter by these transcription factors was also redox-sensitive. This response was mediated through the TNF-R1 receptor (p55), and not the TNF-R2 (p75) receptor, although both receptors can be found on pulmonary epithelial cells. Taken together these studies indicate that TNF-alpha-induced redox changes in lung epithelial cells are responsible for the transcriptional activation of IL-8 and that coordinate activation of NF-kappaB and NF-IL-6 mediate the response.

Chemical labyrinthectomy and cochlear implantation for Menière's disease--an effective treatment or a last resort?

The surgical management of Menière's disease presents a difficult and controversial problem and includes various procedures ranging from 'placebo operations' to vestibular nerve section. The situation is even more complex in the case where the only hearing ear is affected. We present a case of severe debilitating vertigo due to Menière's disease that was treated by chemical labyrinthectomy and cochlear implantation. This unique management strategy allowed restoration of useful hearing and relief of vertigo.

Toxic metals stimulate inflammatory cytokines in hepatocytes through oxidative stress mechanisms

Hepatocytes, as well as nonparenchymal cells, secrete proinflammatory cytokines and chemokines that are involved in the pathology of many liver diseases. In particular, tumor necrosis factor-alpha (TNFalpha), as well as members of the CXC family of chemokines, including interleukin (IL)-8 in humans and macrophage inflammatory protein (MIP)-2 in rodents, have been implicated in both damage and repair processes associated with various hepatotoxins. In the liver, cytokine secretion is usually associated with nonparenchymal cells, particularly Kupffer cells. In the present studies, cytokine gene expression and secretion were investigated in hepatocytes treated with cadmium chloride (CdCl2) or vanadium pentoxide (V2O5). Using human Hep G2 cells and freshly isolated rodent hepatocytes, it was demonstrated that metals increase gene expression and secretion of CXC chemokines and TNFalpha. IL-8 and MIP-2 secretion induced either by the metals or H2O2 were inhibited by antioxidants such as tetramethyl-thiourea and N-acetyl-cysteine. In vitro neutralization experiments with TNFalpha and in vivo studies with TNFalpha receptor knockout mice indicated that the metals directly stimulate CXC chemokine secretion without the need for TNFalpha. Taken together these studies indicate that, in addition to other inflammatory mediators and acute phase proteins, cytokines and chemokines are produced by hepatocytes, which may participate in hepatotoxic responses. The events responsible for their expression involve cellular redox changes.

Cytokine expression in hepatocytes: role of oxidant stress

Inflammatory mediators, including cytokines and chemokines, are associated with the pathology of chronic liver disease. Interleukin-8 (IL-8) in humans and macrophage inflammatory protein-2 (MIP-2) in rodents, both members of the C-X-C family of chemokines, are particularly potent neutrophil attractants and have been implicated in chronic liver diseases. In the liver, cytokine secretion is usually associated with non-parenchymal cells, particularly Kupffer cells. In the present studies, chemokine gene expression and secretion were investigated in hepatocytes treated with various stimulators. Using human Hep G2 cells, it was demonstrated that, in contrast to lipopolysaccharides (LPS), both tumor necrosis factor-alpha (TNF-beta) and H2O2 are potent inducers of IL-8, presumably acting via protein kinase C (PKC)-dependent pathways. MIP-2 expression occurred in freshly isolated rat hepatocytes following treatment with TNF-alpha, LPS, and to a lesser degree, H2O2. Both IL-8 and MIP-2 secretion were inhibited, although to varying degrees, by such antioxidants as TMTU, DMSO, catalase, and N-acetylcysteine. Furthermore, in vitro TNF-alpha neutralization experiments and transfection of Hep G2 cells with an IL-8 construct confirmed that TNF-alpha and H2O2 directly stimulate IL-8 secretion. RT-PCR analyses indicated that chemokine secretion induced by these agents operates via increased gene expression. Furthermore, a variety of cytokine genes were found to be expressed by hepatocytes, including MCP-1, cytokine-induced neutrophil chemoattractant (CINC), and IL-6. Taken together, these studies indicate that hepatocytes respond to biologically relevant levels of common activators, including H2O2, to produce cytokines and chemokines that contribute to pathophysiologic and repair processes in the liver.

A leaking aortic aneurysm presenting as a recurrent neck swelling

We present a case of an 82-year-old lady with recurrent neck swelling and a history of intermittent stridor who subsequently developed a contusion over her lower neck and upper chest. The patient collapsed on her way to have a CT scan and died 24 hours later of a leaking aortic aneurysm. At initial presentation the complete resolution of poorly localizing symptoms and signs almost allowed her discharge from hospital.

Language development in a group of very low-birth-weight children whose postauricular myogenic response was tested in infancy

A new instrument for the detection of the postauricular myogenic (PAM) response was used to test the hearing of 106 infants weighing less than or equal to 1,500 g when they were aged 1 to 21 months. Eighty-eight infants showed a positive response at 60 dB hearing level (HL) (normal). The other 18 did not respond; four were found to have sensory neural hearing loss and another six had conductive loss due to secretory otitis media. Of the 106 children, 90 aged 2 years or more (mean 27 months) were living in the United Kingdom, and their language development was assessed. It was normal in 67/75 children whose PAM response had been normal in infancy. The remaining eight children with normal PAM responses in infancy, had language delay. All eight children had problems that were thought to account for the delay, including three with mental retardation, three with cerebral palsy, and two whose families did not speak English. Language development was normal in 11/15 children tested whose PAM responses had been found to be abnormal, including all six whose secretory otitis media had been diagnosed and treated at the time of the PAM test. Delay in language development was found in 3/4 children with sensory neural hearing loss who were available for testing and in one child with overall developmental delay. It is concluded that a positive PAM response at 60 dB HL in infancy indicated hearing adequate for the development of normal speech in otherwise normal children among a group of infants at high risk of hearing loss.

Double-alternation runway performance as a function of inter- and intra-reinforcement odor cues

Two groups of 12 rats served as Ss in a three-phase investigation into the production and utilization of odor cues in the runway. Both groups were trained under double-alternation patterns of reward-nonreward with one group serving as start-box donor-odorants, while the second group actually traversed the runway. During the first two phases the run- Ss were water-reinforced, and the donor-odorants were food-reinforced. The reinforcement schedules for the run and donor-odorant Ss were positively correlated during the first phase and negatively correlated during the second phase. In the third phase both groups were food reinforced and the reinforcement schedules once again positively correlated. The results indicated that significant double-alternation patterning was shown by the run- Ss only in the goal measure during Phases I and II. However, significant patterning was shown in start, run, and goal measures during Phase III, suggesting the specificity of odor cues to deprivational states.