Metabolic insights from mass spectrometry imaging of biofilms: A perspective from model microorganisms

Biofilms are dense aggregates of bacterial colonies embedded inside a self-produced polymeric matrix. Biofilms have received increasing attention in medical, industrial, and environmental settings due to their enhanced survival. Their characterization using microscopy techniques has revealed the presence of structural and cellular heterogeneity in many bacterial systems. However, these techniques provide limited chemical detail and lack information about the molecules important for bacterial communication and virulence. Mass spectrometry imaging (MSI) bridges the gap by generating spatial chemical information with unmatched chemical detail, making it an irreplaceable analytical platform in the multi-modal imaging of biofilms. In the last two decades, over 30 species of biofilm-forming bacteria have been studied using MSI in different environments. The literature conveys both analytical advancements and an improved understanding of the effects of environmental variables such as host surface characteristics, antibiotics, and other species of microorganisms on biofilms. This review summarizes the insights from frequently studied model microorganisms. We share a detailed list of organism-wide metabolites, commonly observed mass spectral adducts, culture conditions, strains of bacteria, substrate, broad problem definition, and details of the MS instrumentation, such as ionization sources and matrix, to facilitate future studies. We also compared the spatial characteristics of the secretome under different study designs to highlight changes because of various environmental influences. In addition, we highlight the current limitations of MSI in relation to biofilm characterization to enable cross-comparison between experiments. Overall, MSI has emerged to become an important approach for the spatial/chemical characterization of bacterial biofilms and its use will continue to grow as MSI becomes more accessible.

Circulatory levels of lysophosphatidylcholine species in obese adolescents: Findings from cross-sectional and prospective lipidomics analyses

BACKGROUND AND AIMS

Obesity has reached epidemic proportions, emphasizing the importance of reliable biomarkers for detecting early metabolic alterations and enabling early preventative interventions. However, our understanding of the molecular mechanisms and specific lipid species associated with childhood obesity remains limited. Therefore, the aim of this study was to investigate plasma lipidomic signatures as potential biomarkers for adolescent obesity.

METHODS AND RESULTS

A total of 103 individuals comprising overweight/obese (n = 46) and normal weight (n = 57) were randomly chosen from the baseline ORANGE (Obesity Reduction and Noncommunicable Disease Awareness through Group Education) cohort, having been followed up for a median of 7.1 years. Plasma lipidomic profiling was performed using the UHPLC-HRMS method. We used three different models adjusted for clinical covariates to analyze the data. Clustering methods were used to define metabotypes, which allowed for the stratification of subjects into subgroups with similar clinical and metabolic profiles. We observed that lysophosphatidylcholine (LPC) species like LPC.16.0, LPC.18.3, LPC.18.1, and LPC.20.3 were significantly (p < 0.05) associated with baseline and follow-up BMI in adolescent obesity. The association of LPC species with BMI remained consistently significant even after adjusting for potential confounders. Moreover, applying metabotyping using hierarchical clustering provided insights into the metabolic heterogeneity within the normal and obese groups, distinguishing metabolically healthy individuals from those with unhealthy metabolic profiles.

CONCLUSION

The specific LPC levels were found to be altered and increased in childhood obesity, particularly during the follow-up. These findings suggest that LPC species hold promise as potential biomarkers of obesity in adolescents, including healthy and unhealthy metabolic profiles.

An Overview of Rhinoplasty Practices: European Academy of Facial Plastic Surgery, Collaborative Cross-Sectional Study

This collaborative European Academy of Plastic Surgery (EAFPS) study aimed to provide an overview of rhinoplasty practices, informing clinician and patient decision making. It is a multicenter cross-sectional study, reported as per Strengthening the Reporting of Observational Studies in Epidemiology guidelines. All EAFPS members were contacted via email, inviting them to participate. Members expressing an interest to participate were asked to anonymously complete a questionnaire, related to rhinoplasties that they performed as first/supervising surgeon over a period from January 1, 2019 to January 1, 2022. A descriptive analysis was performed. One hundred and fifteen surgeons submitted data on 41,259 rhinoplasties from 33 countries. Eighty percent of rhinoplasties were primary, and 20% were secondary. Thirty five percent of primary rhinoplasties were closed and 65% were open. Thirty one percent of primary rhinoplasties were for cosmetic indications, 11% functional and 58% were for both. Of the 8147 secondary rhinoplasties, 44% were closed and 56% were open. Thirty percent were for cosmetic indications, 11% functional, and 59% for both cosmetic and functional. Ninety-one percent of rhinoplasties were performed by ENT surgeons, 3% by plastic surgeons, 5% by maxillofacial surgeons, and 1% were dual (maxillofacial and ENT) trained. One-thousand seven-hundred thirty primary rhinoplasties underwent revision surgery (5%) and 102 secondary rhinoplasties underwent revision surgery (1%). The most commonly reported indications for revision surgery were dorsal asymmetry, nasal blockage, and dissatisfaction with nasal tip. Three percent of rhinoplasties underwent preoperative psychological assessment. To the authors knowledge, this is the largest published rhinoplasty dataset. This study provides an overview of rhinoplasty practices that can be used for benchmarking and to guide clinician and patient decision making. Psychological assessment of prerhinoplasty appears insufficient with higher levels recommended to minimize unsuccessful outcomes. This study showcases the power of collaborative research and may serve as a catalyst for future collaborative facial plastic surgery research.

Differential Spreading of Rhamnolipid Congeners from Pseudomonas aeruginosa

Rhamnolipids are surfactants produced by many Pseudomonad bacteria, including the species Pseudomonas aeruginosa. These rhamnolipids are known to aid and enable numerous phenotypic traits that improve the survival of the bacteria that make them. These surfactants are also important for industrial products ranging from pharmaceuticals to cleaning supplies to cosmetics, to name a few. Rhamnolipids have structural diversity that leads to an array of congeners; however, little is known about the localization and distribution of these congeners in two-dimensional space. Differential distribution of congeners can reduce the uniformity of applications in industrial settings and create heterogeneity within biological communities. We examined the distribution patterns of combinations of rhamnolipids in commercially available mixtures, cell-free spent media, and colony biofilms using mass spectrometry. We found that even in the absence of cells, congeners exhibit different distribution patterns, leading to different rhamnolipid congener distributions on a surface. Congeners with shorter fatty acid chains were more centrally located, while longer chains were more heterogeneous and distally located. We found that congeners with similar structures can distribute differently. Within developing colony biofilms, we found rhamnolipid distribution patterns differed from cell-free environments, lacking simple trends noted in cell-free environments. Most strikingly, we found the distribution patterns of individual congeners in the colony biofilms to be diverse. We note that the congener distribution is far from homogeneous but composed of numerous local microenvironments of varied rhamnolipid congener composition.

The genesis of the PM-JAY health insurance scheme in India: technical and political elements influencing a national reform towards universal health coverage

Many countries are using health insurance to advance progress towards universal health coverage (UHC). India launched the Pradhan Mantri Jan Arogya Yojana (PM-JAY) health insurance scheme in 2018. We examine the political economy context around PM-JAY policy formulation, by examining the perspectives of policy stakeholders shaping decisions around the reform. More specifically, we focus on early policy design at the central (national) level. We use a framework on the politics of UHC reform proposed by Fox and Reich (The politics of universal health coverage in low- and middle-income countries: A framework for evaluation and action. J. Health Polit. Policy Law 2015;40:1023-1060), to categorize the reform into phases and examine the interactions between actors, institutions, interests, ideas and ideology which shaped reform decisions. We interviewed 15 respondents in Delhi between February and April 2019, who were either closely associated with the reform process or subject experts. The ruling centre-right government introduced PM-JAY shortly before national elections, drawing upon policy legacies from prior and state insurance schemes. Empowered policy entrepreneurs within the government focused discourse around ideas of UHC and strategic purchasing, and engaged in institution building leading to the creation of the National Health Authority and State Health Agencies through policy directives, thereby expanding state infrastructural and institutional power for insurance implementation. Indian state inputs were incorporated in scheme design features like mode of implementation, benefit package and provider network, while features like the coverage amount, portability of benefits and branding strategy were more centrally driven. These balanced negotiations opened up political space for a cohesive, central narrative of the reform and facilitated adoption. Our analysis shows that the PM-JAY reform focused on bureaucratic rather than ideological elements and that technical compromises and adjustments accommodating the interests of states enabled the political success of policy formulation. Appreciating these politics, power and structural issues shaping PM-JAY institutional design will be important to understand how PM-JAY is implemented and how it advances UHC in India.

Effect of Micro-Patterned Mucin on Quinolone and Rhamnolipid Profiles of Mucoid Pseudomonas aeruginosa under Antibiotic Stress

Pseudomonas aeruginosa (P. aeruginosa) is commonly implicated in hospital-acquired infections where its capacity to form biofilms on a variety of surfaces and the resulting enhanced antibiotic resistance seriously limit treatment choices. Because surface attachment sensitizes P. aeruginosa to quorum sensing (QS) and induces virulence through both chemical and mechanical cues, we investigate the effect of surface properties through spatially patterned mucin, combined with sub-inhibitory concentrations of tobramycin on QS and virulence factors in both mucoid and non-mucoid P. aeruginosa strains using multi-modal chemical imaging combining confocal Raman microscopy and matrix-assisted laser desorption/ionization-mass spectrometry. Samples comprise surface-adherent static biofilms at a solid-water interface, supernatant liquid, and pellicle biofilms at an air-water interface at various time points. Although the presence of a sub-inhibitory concentration of tobramycin in the supernatant retards growth and development of static biofilms independent of strain and surface mucin patterning, we observe clear differences in the behavior of mucoid and non-mucoid strains. Quinolone signals in a non-mucoid strain are induced earlier and are influenced by mucin surface patterning to a degree not exhibited in the mucoid strain. Additionally, phenazine virulence factors, such as pyocyanin, are observed in the pellicle biofilms of both mucoid and non-mucoid strains but are not detected in the static biofilms from either strain, highlighting the differences in stress response between pellicle and static biofilms. Differences between mucoid and non-mucoid strains are consistent with their strain-specific phenology, in which the mucoid strain develops highly protected biofilms.

Evaluation of the association between a single-nucleotide polymorphism of bone morphogenetic proteins 5 gene and risk of knee osteoarthritis

Background:

Osteoarthritis (OA) is a chronic degenerative disorder probably affected by both genetic and environmental causes. Bone morphogenetic proteins (BMPs) are bone-derived factors that can induce new bone formation. Single-nucleotide polymorphisms (SNPs) of BMP5 gene alters the transcriptional activity of the BMP5 promoter that has been involved in OA susceptibility. This case–control study investigated the association of rs1470527 and rs9382564 SNP of BMP5 gene with susceptibility to knee OA (KOA).

Materials and Methods:

A total of 499 cases with radiographic KOA and 458 age- and sex-matched healthy controls were enrolled. Venous blood samples were obtained from all the cases as well as controls for polymerase chain reaction-restriction fragment length polymorphism.

Results:

The genotype distribution for rs1470527 and rs9382564 SNP was significantly different in cases and controls (P < 0.0001). Within both the SNPs of BMP5 gene, genotype CT and TT were significantly (P < 0.0001) associated with KOA as compared to the CC genotype. T allele of both the studied SNP was significantly associated with KOA (P < 0.0001). The allele frequencies of rs1470527 were 0.56(T) and 0.44(C) in cases and 0.33(T) and 0.67(C) in controls and in rs9382564 were 0.57(C) and 0.43(T) in cases and 0.71(C) and 0.29(T) in controls. Further in relation with clinical severity of OA, we observed signification association of TT genotype with both visual analog scale (P < 0.0001) and Western Ontario and McMaster Universities score (P < 0.05).

Conclusion:

Our results indicate significant association of rs1470527 and rs9382564 polymorphism of BMP5 gene with KOA.

Outcomes of repeat two-stage exchange hip arthroplasty for prosthetic joint infection

Aims

The increasing infection burden after total hip arthroplasty (THA) has seen a rise in the use of two-stage exchange arthroplasty and the use of increasingly powerful antibiotics at the time of this procedure. As a result, there has been an increase in the number of failed two-stage revisions during the past decade. The aim of this study was to clarify the outcome of repeat two-stage revision THA following a failed two-stage exchange due to recurrent prosthetic joint infection (PJI).

Patients and Methods

We identified 42 patients who underwent a two-stage revision THA having already undergone at least one previous two stage procedure for infection, between 2000 and 2015. There were 23 women and 19 men. Their mean age was 69.3 years (48 to 81). The outcome was analyzed at a minimum follow-up of two years.

Results

A satisfactory control of infection and successful outcome was seen in 26 patients (57%). There therefore remained persistent symptoms that either required further surgery or chronic antibiotic suppression in 16 patients (38%). One-third of patients had died by the time of two years’ follow-up.

Conclusion

The rate of failure and complication rate of repeat two-stage exchange THA for PJI is high and new methods of treatment including host optimization, immunomodulation, longer periods between stages, and new and more powerful forms of antimicrobial treatment should be investigated. Cite this article: Bone Joint J 2019;101-B(6 Supple B):110–115.

Superfluous glutamine synthetase activity in Chinese Hamster Ovary cells selected under glutamine limitation is growth limiting in glutamine-replete conditions and can be inhibited by serine

Passaging and expansion of animal cells in lean maintenance medium could result in periods of limitation of some nutrients. Over time, such stresses could possibly result in selection of cells with metabolic changes and contribute to heterogeneity. Here, we investigate whether selection of Chinese Hamster Ovary (CHO) cells under glutamine limitation results in changes in growth under glutamine-replete conditions. In glutamine-limiting medium, compared to control cells passaged in glutamine-rich medium, the selected cells showed higher glutamine synthetase (GS) activity and attained a higher peak viable cell density (PVCD). Surprisingly, in glutamine-replete conditions, selected cells still showed a higher GS activity but a lower PVCD. We show that in glutamine-replete medium, PVCD of selected cells was restored on (a) inhibition of GS activity with methionine sulfoximine, (b) supplementation of aspartate-without affecting GS activity, and (c) supplementation of serine, which is reported to inhibit GS in vitro. Consistent with the reported effect of serine, inhibition of GS activity was observed upon serine supplementation along with reduced growth of cells under glutamine-limiting conditions. The latter observation is important for the design of glutamine-free culture medium and feed used for GS-CHO and GS-NS0. In summary, we show that CHO cells selected under glutamine limitation have superfluous GS activity in glutamine-replete medium, which negatively affects their PVCD. This may be due to its effect on availability of aspartate which was the limiting nutrient for the growth of selected cells in glutamine-replete conditions.

A scalable metabolite supplementation strategy against antibiotic resistant pathogen Chromobacterium violaceum induced by NAD+/NADH+ imbalance

BACKGROUND

The leading edge of the global problem of antibiotic resistance necessitates novel therapeutic strategies. This study develops a novel systems biology driven approach for killing antibiotic resistant pathogens using benign metabolites.

RESULTS

Controlled laboratory evolutions established chloramphenicol and streptomycin resistant pathogens of Chromobacterium. These resistant pathogens showed higher growth rates and required higher lethal doses of antibiotic. Growth and viability testing identified malate, maleate, succinate, pyruvate and oxoadipate as resensitising agents for antibiotic therapy. Resistant genes were catalogued through whole genome sequencing. Intracellular metabolomic profiling identified violacein as a potential biomarker for resistance. The temporal variance of metabolites captured the linearized dynamics around the steady state and correlated to growth rate. A constraints-based flux balance model of the core metabolism was used to predict the metabolic basis of antibiotic susceptibility and resistance.

CONCLUSIONS

The model predicts electron imbalance and skewed NAD/NADH ratios as a result of antibiotics - chloramphenicol and streptomycin. The resistant pathogen rewired its metabolic networks to compensate for disruption of redox homeostasis. We foresee the utility of such scalable workflows in identifying metabolites for clinical isolates as inevitable solutions to mitigate antibiotic resistance.

CHO Cells adapted to inorganic phosphate limitation show higher growth and higher pyruvate carboxylase flux in phosphate replete conditions

Inorganic phosphate (P_i ) is an essential ion involved in diverse cellular processes including metabolism. Changes in cellular metabolism upon long term adaptation to P_i limitation have been reported in E. coli. Given the essential role of P_i , adaptation to P_i limitation may also result in metabolic changes in animal cells. In this study, we have adapted CHO cells producing recombinant IgG to limiting P_i conditions for 75 days. Not surprisingly, adapted cells showed better survival under P_i limitation. Here, we report the finding that such cells also showed better growth characteristics compared to control in batch culture replete with P_i (higher peak density and integral viable cell density), accompanied by a lower specific oxygen uptake rate and cytochrome oxidase activity towards the end of exponential phase. Surprisingly, the adapted cells grew to a lower peak density under glucose limitation. This suggests long term P_i limitation may lead to selection for an altered metabolism with higher dependence on glucose availability for biomass assimilation compared to control. Steady state U-¹³ C glucose labeling experiments suggest that adapted cells have a higher pyruvate carboxylase flux. Consistent with this observation, supplementation with aspartate abolished the peak density difference whereas supplementation with serine did not abolish the difference. This supports the hypothesis that cell growth in the adapted culture might be higher due to a higher pyruvate carboxylase flux. Decreased fitness under carbon limitation and mutations in the sucABCD operon has been previously reported in E. coli upon long term adaptation to P_i limitation, suggestive of a similarity in cellular response among such diverse species. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:749-758, 2017.

Evaluation of a service intervention to improve awareness and uptake of bowel cancer screening in ethnically-diverse areas

BACKGROUND

Uptake of bowel cancer screening is lowest in London, in populations of lower socio-economic status, and in particular ethnic or religious groups.

METHODS

We report on the evaluation of two interventions to improve uptake in an area including populations of low socio-economic status and considerable ethnic diversity. The interventions were face-to-face health promotion on bowel cancer screening at invitees' general practice and health promotion delivered by telephone only. Nine large general practices in East London were chosen at random to offer face-to-face health promotion, and nine other large practices to offer telephone health promotion, with 24 practices of similar size as comparators. Data at practice level were analysed by Mann-Whitney-Wilcoxon tests and grouped-logistic regression.

RESULTS

There were 2034 invitees in the telephone intervention practices, 1852 in the face-to-face intervention practices and 5227 in the comparison practices. Median gFOBt kit uptake in the target population (aged 59-70) was 46.7% in the telephone practices, 43.8% in the face-to-face practices and 39.1% in the comparison practices. Significant improvements in the odds of uptake were observed following telephone intervention in both males (OR=1.39, 95% CI=1.20-1.61, P<0.001) and females (OR=1.49, 95% CI=1.29-1.73, P<0.001), while the face-to-face intervention mainly impacted uptake in males (OR=1.23, 95% CI=1.10-1.36), P<0.001) but did not lead to a significant increase in females (OR=1.12, 95% CI=0.96-1.29, P=0.2).

CONCLUSIONS

Personally delivered health promotion improved uptake of bowel cancer screening in areas of low socio-economic status and high ethnic diversity. The intervention by telephone appears to be the most effective method.

Association of cytochrome P450 2C9 polymorphism with locally advanced head and neck squamous cell carcinoma and response to concurrent cisplatin-based radical chemoradiation

Aims:

The aim of the present study is to investigate the association between polymorphism of cytochrome P450 2C9 (CYP2C9) enzyme with head and neck squamous cell carcinoma (HNSCC) and response in patients receiving cisplatin-based radical chemoradiation (CT-RT).

Materials and Methods:

Four hundred and sixty patients suffering from locally advanced HNSCC and an equal number of healthy controls were genotyped for CYP2C9*2 and CYP2C9*013, leading to poor metabolizers (PMs) by polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP). Each case was assessed thoroughly for treatment response as per the World Health Organization (WHO) criteria.

Results and Analysis:

The frequency of heterozygous genotypes of both CYP2C9*2 (27.8%) and CYP2C9*3 (25%) were found to be significantly higher in the HNSCC cases as compared to the healthy controls. Tobacco intake in the form of chewing or smoking and alcohol intake resulted in several folds increase in the risk to HNSCC in the cases carrying variant genotypes of CYP2C9*2 or CYP2C9*013. Further, majority of the cases assessed for response (n = 436) carrying variant alleles of CYP2C9*2 (69.6%) or CYP2C9*3 (65.2%) were found to respond poorly to cisplatin-based radical CT-RT.

Conclusion:

The data suggests a significant association of the CYP2C9 polymorphism with HNSCC and treatment outcome underlining the importance of pretherapeutic genotyping in determining the treatment protocol.

Neuroprotective potentials of neurotrophin rich olfactory ensheathing cell's conditioned media against 6OHDA-induced oxidative damage

On the basis of recent reports, we propose that impaired neurotrophin signaling (PI3k/Akt), low antioxidant levels, and generation of reactive oxygen species (ROS) conjointly participate in the progressive events responsible for the dopaminergic cell loss in Parkinson's disease (PD). In the present study we tried to target these deficits collectively through multiple neurotrophic factors (NTFs) support in the form of Olfactory Ensheathing Cell's Conditioned Media (OEC CM) using human SH-SY5Y neuroblastoma cell line exposed to 6 hydroxydopamine (6OHDA). 6OHDA exposure induced, oxidative stress-mediated apoptotic cell death viz. enhanced ROS generation, diffused cytosolic cytochrome c (cyt c), impaired Bcl-2: Bax levels along with decrease in GSH content. These changes were accompanied by loss in Akt phosphorylation and TH levels in SH-SY5Y cells. OEC CM significantly checked apoptotic cell death by preserving pAkt levels which coincided with enhanced GSH and suppressed oxidative injury. Functional integrity of OEC CM supported cells was evident by maintained tyrosine hydroxylase (TH) expression. Intercepting Akt signaling by specific inhibitor LY294002 blocked the protective effect. Taken together our findings provide important evidence that the key to protective effect of multiple NTF support via OEC CM is enhanced Akt survival signaling which promotes antioxidant defense leading to suppression of oxidative damage.

Reduction in interval cancer rates following the introduction of two-view mammography in the UK breast screening programme

BACKGROUND

The introduction of two-view mammography at incident (subsequent) screens in the National Health Service Breast Screening Programme (NHSBSP) has led to an increased number of cancers detected at screen. However, the effect of two-view mammography on interval cancer rates has yet to be assessed.

METHODS

Routine screening and interval cancer data were collated from all screening programmes in the United Kingdom for women aged 50-64, screened between 1 April 2003 and 31 March 2005. Interval cancer rates were compared based on whether two-view mammography was in use at the last routine screen.

RESULTS

The reduction in interval cancers following screening using two-view mammography compared with one view was 0.68 per 1,000 women screened. Overall, this suggests the introduction of two-view mammography at incident screen was accompanied by a 15-20% reduction in interval cancer rates in the NHSBSP.

CONCLUSION

The introduction of two-view mammography at incident screens is associated with a reduction in incidence of interval cancers. This is consistent with previous publications on a contemporaneous increase in screen-detected cancers. The results provide further evidence of the benefit of the use of two-view mammography at incident screens.

A preliminary evaluation of plasma b-type natriuretic peptide as a screening test for left ventricular diastolic dysfunction in non-cardiac intensive care

Left ventricular filling and thus diastolic function are frequently monitored and managed in critical care. However, scant data exist regarding possible screening tests for diastolic dysfunction in the intensive care unit (ICU). The present study aimed to evaluate plasma b-type natriuretic peptide (BNP) as a marker of diastolic dysfunction in a single-centre cohort of 'non-cardiac' ICU patients. The ICU is non-cardiac in that it provides mixed medical/surgical services with the exception of cardiology, cardiac surgery and solid organ transplantation. Clinical data were recorded over the first 24 hours of ICU stay for 32 consecutive patients. Transthoracic echocardiogram and blood collection for BNP assay were then performed. Diastolic dysfunction was demonstrated in 34% (n=11). Mean ± standard deviation BNP values were higher with diastolic dysfunction (238 ± 195 vs 72 ± 78 pg/ml; P=0.003). A BNP threshold of >43 pg/ml yielded a sensitivity of 80% and a specificity of 59%; area under the receiver operating characteristic curve was 0.82. BNP correlated independently with E/e' (R=0.425; P=0.015) (E/e': peak early transmitral velocity [E]/early diastolic mitral annular velocity [e']) but not left ventricular ejection fraction (P=0.8), illness severity (Acute Physiological and Chronic Health Evaluation II; P=0.3) or fluid balance (P=0.4). Diastolic dysfunction was common in this cohort of non-cardiac ICU patients and was independently associated with a significantly higher BNP. The potential application as a screening test for diastolic dysfunction is likely to require a threshold lower than previously proposed for heart failure.

A randomised trial of weekend and evening breast screening appointments

Background:

There is a need to research interventions that improve access to and convenience of breast cancer screening services.

Methods:

We conducted a randomised trial comparing invitations to out-of-hours appointments with standard office hour appointments. Women who were to be invited for routine breast screening were randomised (3 : 1 : 1 : 1) to one of these screening invitations: standard office hour appointment, office hour appointment with the option to change to an out-of-hours appointment, weekday evening appointment, or weekend appointment.

Results:

A total of 9410 women were invited to an office hour, 3519 to an office hour with the option to change, 3271 to a weekday evening, and 3162 to a weekend appointment. The offer of an initial out-of-hours appointment was associated with a non-significant decrease in attendance rates (73.7% vs 74.1%). The highest attendance was observed in the group offered an initial office hour appointment with the option to change to out-of-hours (76.1% vs 73.3% for standard office hour, P=0.001), with 7% of invitees exercising the option to change.

Conclusion:

The optimum strategy for improving attendance at breast screening is to offer a traditional office hour appointment and including in the letter of invitation an option to change to an evening or weekend appointment if wished.

Salsolinol induced apoptotic changes in neural stem cells: amelioration by neurotrophin support

Salsolinol (SAL), a catechol isoquinoline has invited considerable attention due to its structural similarity with dopaminergic neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Its high endogenous presence in Parkinsonian brain implicated its possible association with the disease process. SAL is also present in alcohol beverages and certain food materials and can get access to brain especially in conditions of immature or impaired BBB. Besides this, the effect of SAL on neural stem cells (NSCs) which are potential candidates for adult neurogenesis and transplantation mediated rejuvenating attempts for Parkinson's disease (PD) brain has not been known so far. NSCs in both the cases have to overcome suppressive cues of diseased brain for their survival and function. In this study we explored the toxicity of SAL toward NSCs focusing on apoptosis and status of PI3K survival signaling. NSCs cultured from embryonic day 11 rat fetal brain including those differentiated to TH(+ve) colonies, when challenged with SAL (1-100μM), elicited a concentration and time dependent cell death/loss of mitochondrial viability. 10μM SAL on which significant mitochondrial impairment initiated was further used to study mechanism of toxicity. Morphological impairment, enhanced TUNEL positivity, cleaved caspase-3 and decreased Bcl-2:Bax suggested apoptosis. Sal toxicity coincided with reduced pAkt level and its downstream effectors: pCREB, pGSK-3β, Bcl-2 and neurotrophins GDNF, BDNF suggesting repressed PI3K/Akt signaling. Multiple neurotrophic factor support in the form of Olfactory Ensheathing Cell's Conditioned Media (OEC CM) potentially protected NSCs against SAL through activating PI3K/Akt pathway. This was confirmed on adding LY294002 the PI3K inhibitor which abolished the protection. We inferred that SAL exerts substantial toxicity toward NSCs. These findings will lead to better understanding of endogenous threats that might affect the fate of transplanted NSCs and their probable antidotes.

Bacterial localization and viability assessment in human ex vivo dentinal tubules by fluorescence confocal laser scanning microscopy

AIM

To develop a convenient method for the localization and quantification of live and dead bacteria in human ex vivo mineralized dentinal tubules.

METHODOLOGY

The roots from human single-rooted teeth (n = 12) were infected with Enterococcus faecalis V583 and either treated with calcium hydroxide paste or left untreated; six control roots were uninoculated and untreated. Following further incubation, roots were stained with fluorescent DNA-binding reagents, washed thoroughly, sectioned and examined by confocal laser scanning microscopy. Computer-assisted determinations of fluorescence (bacterial viability) were compared statistically.

RESULTS

Bacteria were distributed in the tubules throughout the length of the roots but tubule penetration distance was slightly reduced in the apical sections. There was no significant difference in bacterial tubule penetration between roots from different teeth and small standard deviations indicated reproducibility appropriate for experimental application. Following treatment with calcium hydroxide paste, live and dead bacteria were readily distinguishable by contrasting green and red fluorescence. Bacterial viability determinations amongst roots treated in the same way were not significantly different, and the small standard deviation is commensurate with experimental application.

CONCLUSIONS

Fluorescent viability staining is a convenient, accurate and reproducible method for localizing and quantifying live and dead bacteria in human ex vivo mineralized dentinal tubules.

Using community wealth ranking to identify the poor for subsidies: a case study of community-based health insurance in Nouna, Burkina Faso

Access to health-care is low in developing countries. Poor people are less likely to seek care than those who are better off. Community-based health insurance (CBI) aims to improve healthcare utilisation by removing financial barriers, unfortunately CBI has been less effective in securing equity than expected. Poor people, who probably require greater protection from catastrophic health expenses, are less likely to enrol in such schemes. Therefore, it is important to implement targeted interventions so that the most in need are not left out. CBI has been offered to a district in Burkina Faso, comprising 7762 households in 41 villages and the district capital of Nouna since 2004. Community wealth ranking (CWR) was used in 2007 to identify the poorest quintile of households who were subsequently offered insurance at half the usual premium rate. The CWR is easy to implement and requires minimal resources such as interviews with local informants. As used in this study, the agreement between the key informants was more (37.5%) in the villages than in Nouna town (27.3%). CBI management unit only received nine complaints from villagers who considered that some households had been wrongly identified. Among the poorest, the annual enrolment increased from 18 households (1.1%) in 2006 to 186 (11.1%) in 2007 after subsidies. CWR is an alternative methodology to identify poor households and was found to be more cost and time efficient compared to other methods. It could be successfully replicated in low-income countries with similar contexts. Moreover, targeted subsidies had a positive impact on enrolment.

Effect of lindane on hepatic and brain cytochrome P450s and influence of P450 modulation in lindane induced neurotoxicity

Oral administration of lindane (2.5, 5, 10 and 15 mg/kg, body weight) for 5 days was found to produce a dose-dependent increase in the activity of P450 dependent 7-ethoxyresorufin-O-deethylase (EROD), 7-pentoxyresorufin-O-dealkylase (PROD) and N-nitrosodimethylamine demethylase (NDMA-d) in rat brain and liver. A significant increase in the hepatic and brain P450 monooxygenases was also observed when the duration of exposure of low dose (2.5 mg/kg) of lindane was increased from 5 days to 15 or 21 days. As observed with different doses, the magnitude of induction in the activity of P450 monooxygenases was several fold higher in liver microsomes when compared with the brain. Western blotting studies have indicated that the increase in the P450 enzymes could be due to the increase in the expression of P450 1A1/1A2, 2B1/2B2 and 2E1 isoenzymes. In vitro studies using organic inhibitors specific for individual P450 isoenzymes and antibody inhibition experiments have further demonstrated that the increase in the activity of PROD, EROD and NDMA-d are due to the increase in the levels of P450 2B1/2B2, 1A1/1A2 and 2E1 isoenzymes, respectively. Induction studies have further shown that while pretreatment of 3-methylcholanthrene (MC), an inducer of P4501A1/1A2, did not produce any significant effect in the incidence of lindane induced convulsions, pretreatment with phenobarbital (PB), an inducer of P450 2B1/2B2 or ethanol, an inducer of P450 2E1 catalysed reactions, significantly increased the incidence of lindane induced convulsions. Similarly, when the P450-mediated metabolism of lindane was blocked by cobalt chloride incidence of convulsions was increased in animals treated with lindane indicating that lindane per se or its metabolites formed by PB or ethanol inducible P450 isoenzymes are involved in its neurobehavioral toxicity.

Effect of pretreatment of cytochrome P450 (P450) modifiers on neurobehavioral toxicity induced by deltamethrin

To investigate the involvement of cytochrome P450 (P450) enzyme induction and the effect of different P450 modifiers in the neurobehavioral toxicity of deltamethrin, deltamethrin (10 mg/kg; orally for 1 day) was administered to young male albino Wistar rats, or in rats pretreated with phenobarbital (PB; 80 mg/kg, ip for 5 days), an inducer of P450 2B1/2B2 or 3-methylcholanthrene (MC; 30 mg/kg, ip for 5 days), an inducer of P450 1A1/1A2 or cobalt chloride (CoCl(2); sc for 2 days), a depletor of P450s. The administration of PB or MC or CoCl(2) alone did not produced any symptoms of neurobehavioral toxicity. While a single oral administration of deltamethrin produced tremors in two out of 10 rats and decreased the spontaneous locomotor activity, pretreatment with MC or PB potentiated the deltamethrin induced neurobehavioral toxicity with 50% of the treated rats exhibiting tremors. Half of the animals pretreated with MC prior to exposure to deltamethrin also exhibited choreoathetosis. The decrease in the spontaneous locomotor activity was found to be much more significant in PB- or MC-pretreated animals exposed to deltamethrin. In contrast to the pretreatment with inducers, rats pretreated with CoCl(2) exhibited no symptoms of tremors or choreoathetosis, indicating that a reactive metabolite of deltamethrin is formed by P450 catalysed reactions which is involved in the neurobehavioral toxicity of deltamethrin.

Cytochrome P450 2E1 dependent catalytic activity and lipid peroxidation in rat blood lymphocytes

To investigate the similarities in the catalytic activity of blood lymphocyte P450 2E1 in blood lymphocyte with the liver isoenzyme, NADPH dependent lipid peroxidation and activity of N-nitrosodimethyamine demethylase (NDMA-d) was studied in rat blood lymphocytes. Blood lymphocytes were found to catalyse NADPH dependent (basal) lipid peroxidation and demethylation of N-nitrosodimethylamine (NDMA). Pretreatment with ethanol or pyrazole or acetone resulted in significant increase in the NADPH dependent lipid peroxidation and the activity of NDMA-d in blood lymphocytes and liver microsomes. In vitro addition of CCl(4) to the blood lymphocytes isolated from control or ethanol pretreated rats resulted in an increase in the NADPH dependent lipid peroxidation. Significant inhibition of the basal and CCl(4) supported NADPH dependent lipid peroxidation and NDMA-d activity in blood lymphocytes isolated from control or ethanol pretreated rats by dimethyl formamide or dimethyl sulfoxide or hexane, solvents known to inhibit P450 2E1 catalysed reactions in liver and anti- P450 2E1, have indicated the role of P450 2E1 in the NADPH dependent lipid peroxidation in rat blood lymphocytes. The data indicating similarities in the NADPH dependent lipid peroxidation and NDMA-d activity in blood lymphocyte with the liver microsome have provided evidence that blood lymphocyte P450 2E1 could be used as a surrogate to monitor and predict hepatic levels of the enzyme.

Antistress effects of bacosides of Bacopa monnieri: modulation of Hsp70 expression, superoxide dismutase and cytochrome P450 activity in rat brain

The antistress effect of bacosides of Brahmi (Bacopa monnieri, BBM), dissolved in distilled water, was -studied in adult male Sprague Dawley rats by administering oral doses of 20 and 40 mg/kg for 7 consecutive days. In half of the animals treated with 20 or 40 mg/kg of BBM, stress was given 2 h after the last dose. Stress was also administered to the animals treated with distilled water alone. BBM, at both doses, did not induce a significant change in the expression of Hsp70 in any brain region studied while stress alone produced a significant increase in the Hsp70 expression in all the brain regions. A significant decrease in the activity of superoxide dismutase (SOD) was evident in the hippocampus with the lower dose of BBM and in animals given stress alone, while an increase in the activity of SOD was observed in the brain regions with the higher dose of BBM. An increase in the activity of cytochrome P450 (P450) dependent 7-pentoxyresorufin-o-dealkylase (PROD) and 7-ethoxyresorufin-o-deethylase (EROD) was observed in all the brain regions after exposure to stress alone and with both doses of BBM although the magnitude of induction of P450 expression was less with a higher dose of BBM. Interestingly, stress when given to the animals pretreated with BBM for 7 days resulted in a decrease in Hsp70 expression in all the brain regions with a significant decrease occurring only in the hippocampus. Likewise the activity of SOD was found to be further reduced in all the brain regions in the animals treated with the lower dose of BBM followed by stress. However, when stress was given to the animals pretreated with the higher dose of BBM, a significant increase in the enzyme activity was observed in the cerebral cortex and in the rest of the brain while the activity of SOD was reduced to a much greater extent in the cerebellum and in the hippocampus. Likewise, the activity of P450 enzymes was found to be restored to almost control levels in the animals given stress and pretreated with the higher dose of BBM, while a lesser degree of induction, compared with animals treated with BBM or stress alone, was observed in the animals pretreated with the lower dose of BBM and given stress. The data indicate that BBM has potential to modulate the activities of Hsp70, P450 and SOD thereby possibly allowing the brain to be prepared to act under adverse conditions such as stress.

Naively changing HAART

BACKGROUND

Few UK studies have systematically investigated which antiretroviral therapy (ART) combinations HIV-infected people are commenced on, when they start and reasons for stopping or changing their regimens.

OBJECTIVE

To describe when HIV-infected ART-naive patients started first-, second- or third-line triple ART, classes of drugs prescribed and whether stopping ART was associated with virological, immunological or clinical indicators of treatment failure.

DESIGN

A multicentre prospective open cohort study, employing the National Prospective Monitoring System on the use, cost and outcome of HIV service provision in UK hospitals-HIV Health-economics Collaboration (NPMS-HHC).

SETTING

Five hundred and eighty-five ART-naive patients seen in one London and two non-London HIV clinics between 1 January 1998 and 31 December 1999.

RESULTS

Of 4,044 HIV-infected individuals seen, 585 (15%) were ART naive. Median time interval (interquartile range, IQR) between HIV diagnosis and starting triple ART was 800 (63-2,094) days. Median CD4 count when first diagnosed with HIV infection was 278 (IQR 127-481) cells/ micro L which dropped to 190 (IQR 86-297) cells/ micro L when starting triple ART. Of these 585 patients, 162 started second-line and 46 third-line ART during the study period. Of those patients who stopped ART, 51% did not have evidence of virological, immunological or clinical indicators of therapy failure.

CONCLUSIONS

Reasons for the delay between diagnosis of HIV infection and starting ART are varied. The large proportion of individuals who stopped ART for reasons other than virological, immunological or clinical indicators of therapy failure, are most likely due to drug-associated toxicity. Both of these findings need to be elucidated in greater detail through prospective studies.