Subjective expectation of reaching age 85: agreement with population statistics and association with behavioral and psychological factors.

BACKGROUND: It is not clearly known how well Danes estimate their chances of reaching the average life expectancy and whether identifiable population subgroups misestimate their life expectancy, and potentially also investments and savings in health and pensions. Therefore, in this study, we examined on the individual level whether subjective life expectancy is in line with the statistically calculated chance of reaching age 85, and further explored the psychological and behavioral factors associated with under or overestimation. METHODS: We opted for a cross-sectional survey design based on a sample of 5,379 Danish citizens aged 50-70 years, returning a web-based questionnaire with socio-demographic data supplemented from a national registry. Average participant estimates of their chance of reaching age 85 for each age range and sex group were compared with actuarial data. We then performed multiple linear regression analyses to examine factors associated with the subjective expectancy of reaching age 85 years. RESULTS: We found that 32% of females and 23% of males reported 100% certainty of reaching age 85, and average expected survival chance exceeded the statistically predicted survival chance for 23% of males and 16% for females in age-ranges 50-60 and 61-70. Our multivariable analysis found that health literacy, internal health locus of control, willingness to take health risks, self-rated health, and health and life satisfaction all showed a significant positive association with expectation of reaching age 85. Moreover, those on daily medications, ex- or current smokers, and heavy drinkers were significantly less optimistic about reaching age 85. CONCLUSIONS: Particularly for the population groups with inaccurate life expectancies, the significant associations with psychological and behavioral factors open a way for initiatives based on behavior change theories to reach a better agreement between subjective and statistical life expectancy.

Prolongation of disease-free life: When is the benefit sufficient to warrant the effort of taking a preventive medicine?

The prolongation of disease-free life (PODL) required by people to be willing to accept an offer of a preventive treatment is unknown. Quantifying the required benefits could guide information and discussions about preventive treatment. In this study, we investigated how large the benefit in prolongation of a disease-free life (PODL) should be for individuals aged 50-80 years to accept a preventive treatment offer. We used a cross-sectional survey design based on a representative sample of 6847 Danish citizens aged 50-80 years. Data were collected in 2019 through a web-based standardized questionnaire administered by Statistics Denmark, and socio-demographic data were added from a national registry. We analyzed the data with chi-square tests and stepwise multinomial logistic regression. The results indicate that the required minimum benefit from the preventive treatment varied widely between individuals (1-week PODL = 14.8%, ≥4 years PODL = 39.2%), and that the majority of individuals (51.1%) required a PODL of ≥2 years. The multivariable analysis indicate that education and income were independently and negatively associated with requested minimum benefit, while age and smoking were independently and positively associated with requested minimum benefit to accept the preventive treatment. Most individuals aged 50-80 years required larger health benefits than most preventive medications on average can offer. The data support the need for educating patients and health care professionals on how to use average benefits when discussing treatment benefits, especially for primary prevention.

Association between health literacy, general psychological factors, and adherence to medical treatment among Danes aged 50-80 years.

BACKGROUND: Understanding behavioral factors associated with low health literacy (HL) is relevant for health care providers to better support their patients' health and adherence to preventive treatment. In this study, we aim to study associations between low HL and socio-demographic characteristics, medication-related perceptions and experience, as well as general psychological factors among patients aged 50-80 years. METHODS: We used a cross-sectional survey design based on a representative group of 6,871 Danish citizens aged 50-80 years returning a web-based questionnaire with socio-demographic data added from a national registry. Chi-square tests were conducted to analyze associations between low HL and daily use of medication and self-rated health. Chi-square tests and binary logistic regression were conducted for analyzing data from respondents using prescribed medicines daily (N = 4,091). RESULTS: Respondents with low HL were more often on daily medications (19 % [777/4,091] vs. 16 % [436/2,775]; P < 0.001) and were more likely to have poorer self-rated health (P < 0.001). Among patients on daily medications, low HL was significantly higher among men and those with lower educational attainment and lower family income. Low HL was independently and positively associated with perceptions that taking prescribed medicines daily is difficult and time-consuming, with forgetting to take prescribed medicines, and with lower satisfaction with life and poor self-assessed health. CONCLUSIONS: Our study provides information that patients aged 50-80 years with low HL are challenged on their adherence to treatment plans which is not only related to traditional sociodemographic factors but also on perceptions related to taking medication per se.

Evolution of the ß-lactam-resistant Streptococcus pneumoniae PMEN3 clone over a 30 year period in Barcelona, Spain.

Objectives: To analyse the epidemiology and genetic evolution of PMEN3 (Spain9V-156), a penicillin-non-susceptible clone of Streptococcus pneumoniae, causing invasive pneumococcal disease (IPD) in Barcelona during 1987-2016. Methods: WGS was performed on 46 representative isolates and the data were used to design additional molecular typing methods including partial MLST, PCR-RFLP and detection of surface-exposed proteins and prophages, to assign the remaining isolates to lineages. The isolates were also subjected to antimicrobial susceptibility testing. Results: Two hundred and twenty-seven adult cases of IPD caused by PMEN3 were identified. PMEN3 caused mainly pneumonia (84%) and the 30 day mortality rate was 23.1%. Evidence of recombination events was found, mostly in three regions, namely the capsular operon (associated with capsular switching) and adjacent regions containing pbp2x and pbp1a, the murM gene and the pbp2b-ddl region. Some of these genetic changes generated successful new variant serotype lineages, including one of serotype 11A that is not included in the current PCV13 vaccine. Other genetic changes led to increased MICs of ß-lactams. Notably, most isolates also harboured prophages coding for PblB-like proteins. Despite these adaptations, the ability of this clone to cause IPD remained unchanged over time, highlighting the importance of its core genetic background. Conclusions: Our study demonstrated successful adaptation of PMEN3 to persist over time despite the introduction of broader antibiotics and conjugate vaccines. In addition to enhancing understanding of the molecular evolution of PMEN3, these findings highlight the need for the development of non-serotype-based vaccines to fight pneumococcal infection.

Genomic analysis of 495 vancomycin-resistant Enterococcus faecium reveals broad dissemination of a vanA plasmid in more than 19 clones from Copenhagen, Denmark.

OBJECTIVES: From 2012 to 2014, there has been a huge increase in vancomycin-resistant (vanA) Enterococcus faecium (VREfm) in Copenhagen, Denmark, with 602 patients infected or colonized with VREfm in 2014 compared with just 22 in 2012. The objective of this study was to describe the genetic epidemiology of VREfm to assess the contribution of clonal spread and horizontal transfer of the vanA transposon (Tn1546) and plasmid in the dissemination of VREfm in hospitals. METHODS: VREfm from Copenhagen, Denmark (2012-14) were whole-genome sequenced. The clonal structure was determined and the structure of Tn1546-like transposons was characterized. One VREfm isolate belonging to the largest clonal group was sequenced using long-read technology to close a 37 kb vanA plasmid. RESULTS: Phylogeny revealed a polyclonal structure where 495 VREfm isolates were divided into 13 main groups and 7 small groups. The majority of the isolates were located in three groups (n = 44, 100 and 218) and clonal spread of VREfm between wards and hospitals was identified. Five Tn1546-like transposon types were identified. A dominant truncated transposon (type 4, 92%) was spread across all but one VREfm group. The closed vanA plasmid was highly covered by reads from isolates containing the type 4 transposon. CONCLUSIONS: This study suggests that it was the dissemination of the type 4 Tn1546-like transposon and plasmid via horizontal transfer to multiple populations of E. faecium, followed by clonal spread of new VREfm clones, that contributed to the increase in and diversity of VREfm in Danish hospitals.

ALFAXALONE ANESTHESIA IN THE BENGALESE FINCH ( LONCHURA DOMESTICA).

The objective of this study was to evaluate the use of alfaxalone in a small passerine species. A dose-response trial was conducted whereby 10, 30, and 50 mg/kg alfaxalone was administered subcutaneously (SC) to 10 Bengalese finches ( Lonchura domestica) in a randomized complete crossover study design. Subsequently, a similar protocol was used to compare 30 mg/kg alfaxalone alone or combined with either 0.7 mg/kg midazolam or 1 mg/kg butorphanol SC. Induction and recovery times were recorded and depth of anesthesia monitored at 5-min intervals throughout each procedure. Functional oxygen saturation and pulse rates were measured with a pulse oximeter at 15 min after administration of the anesthetic agent(s). Dose-dependent decreases in induction time and prolongation of anesthetic duration were seen with increasing alfaxalone dosage. Alfaxalone combined with midazolam resulted in faster inductions, and the addition of both midazolam and butorphanol resulted in longer durations of anesthesia than alfaxalone alone. The addition of midazolam significantly decreased the pulse rate at 15 min compared with alfaxalone alone. Alfaxalone was found to be an effective agent for inducing anesthesia when administered subcutaneously, and no complications were observed. Increasing the dose, and combining with a benzodiazepine or opioid increased the duration of anesthesia with minimal or no effects on respiratory or pulse rates, within the dose range investigated.

Associations between patients' adherence and GPs' attitudes towards risk, statin therapy and management of non-adherence--a survey and register-based study.

BACKGROUND: Previous studies suggest that doctors' personal lifestyle, risk taking personality and beliefs about risk reducing therapies may affect their clinical decision-making. Whether such factors are further associated with patients' adherence with medication is largely unknown. OBJECTIVE: To estimate associations between GPs' attitudes towards risk, statin therapy and management of non-adherence and their patients' adherence, and to identify subgroups of GPs with poor patient adherence. METHODS: All Danish GPs were invited to participate in an online survey. We asked whether they regarded statin treatment as important, how they managed non-adherence and whether non-adherence annoyed them. The Jackson Personality Inventory-revised was used to measure risk attitude. The GPs' responses were linked to register data on their patients' redeemed statin prescriptions. Mixed effect logistic regression was used to estimate associations between patient adherence and GPs' attitudes. Adherence was estimated by the proportion of days covered in a 1-year period using an 80% cut-off. RESULTS: We received responses from 1398 GPs (42.2%) who initiated statin therapy in 12 192 patients during the study period. In total 6590 (54.1%) of these patients were adherent. Patients who had GPs rarely assessing their treatment adherence were less likely to be adherent than those who had GPs assessing their patients' treatment adherence now and then, odds ratio (OR) 0.86 [confidence interval (CI) 0.77-0.96]. No other associations were found between patients' adherence and GPs' attitudes. CONCLUSIONS: Our findings suggest that GPs' attitudes to risk, statin therapy or management of non-adherence are not significantly associated with their patients' adherence.

Aquatic Bird Bornavirus 1 in Wild Geese, Denmark.

To investigate aquatic bird bornavirus 1 in Europe, we examined 333 brains from hunter-killed geese in Denmark in 2014. Seven samples were positive by reverse transcription PCR and were 98.2%-99.8% identical; they were also 97.4%-98.1% identical to reference strains of aquatic bird bornavirus 1 from geese in North America.

Multiple hospital outbreaks of vanA Enterococcus faecium in Denmark, 2012-13, investigated by WGS, MLST and PFGE.

OBJECTIVES: In Denmark, the incidence of vancomycin-resistant Enterococcus faecium (VREfm) has increased since 2012. The aim of this study was to investigate the epidemiology and clonal relatedness of VREfm isolates in Danish hospitals in 2012-13 using WGS. The second aim was to evaluate if WGS-based typing could replace PFGE for typing of VREfm. METHODS: A population-based study was conducted including all VREfm isolates submitted for national surveillance from January 2012 to April 2013. All isolates were investigated by WGS, MLST and PFGE. RESULTS: One-hundred and thirty-two isolates were included. The majority of the isolates were from clinical samples (77%). Gastroenterology/abdominal surgery (29%) and ICUs (29%) were the predominant departments with VREfm. Genomics revealed a polyclonal structure of the VREfm outbreak. Seven subgroups of 3-44 genetically closely related isolates (separated by <17 SNPs) were identified using WGS. Direct or indirect transmission of VREfm between patients and intra- and inter-regional spreading clones was observed. We identified 10 STs. PFGE identified four major clusters (13-43 isolates) and seven minor clusters (two to three isolates). The results from the typing methods were highly concordant. However, WGS-based typing had the highest discriminatory power. CONCLUSIONS: This study emphasizes the importance of infection control measures to limit transmission of VREfm between patients. However, the diversity of the VREfm isolates points to the fact that other important factors may also affect the VREfm increase in Denmark. Finally, WGS is suitable for typing of VREfm and has replaced PFGE for typing of VREfm in Denmark.

Feasibility of smartphone diaries and personal dosimeters to quantitatively study exposure to ultraviolet radiation in a small national sample.

BACKGROUND: In 2007, a national skin cancer prevention campaign was launched to reduce the UV exposure of the Danish population. To improve campaign evaluation a questionnaire validation using UV-dosimeters was initiated. AIM: To show the feasibility of dosimeters for national representative studies and of smartphones as a data collection tool. MATERIALS AND METHODS: Participants were sent a dosimeter which they wore for 7 days, received a short diary questionnaire by text message each day and subsequently a longer questionnaire. Correlation between responses from questionnaire, smartphone diaries and dosimeters were examined. RESULTS: This study shows a 99.5% return rate (n = 205) of the dosimeters by ordinary mail and high response-rates for a smartphone questionnaire dairy. Correlation coefficients for outdoor-time reported through smartphones and dosimeters as average by week 0.62 (0.39-0.77), P < 0.001 (n = 40). Correlation coefficient for outdoor time estimated by questionnaire and dosimeters were 0.42 (0.11-0.64), P = 0.008. The subjective perception of the weather was the only covariate significantly influencing questionnaire estimates of actual outdoor exposure. We showed that dosimeter studies are feasible in national settings and that smartphones are a useful tool for monitoring and collecting UV behavior data. CONCLUSION: We found diary data reported on a daily basis through smartphones more strongly associated with actual outdoor time than questionnaire data. Our results demonstrate tools and possible considerations for executing a UV behavior questionnaire validation.

Long-term weight loss in a 24-month primary care-anchored telehealth lifestyle coaching program: Randomized controlled trial.

Long-term weight loss can reduce the risk of type 2 diabetes for people living with obesity and reduce complications for patients diagnosed with type 2 diabetes. We investigated whether a telehealth lifestyle-coaching program (Liva) leads to long-term (24 months) weight loss compared to usual care. In a randomized controlled trial, n = 340 participants living with obesity with or without type 2 diabetes were enrolled and randomized via an automated computer algorithm to an intervention group (n = 200) or to a control group (n = 140). The telehealth lifestyle-coaching program comprised of an initial one-hour face-to-face motivational interview followed by asynchronous telehealth coaching. The behavioural change techniques used were enabled by individual live monitoring. The primary outcome was a change in body weight from baseline to 24 months. Data were assessed for n = 136 participants (40%), n = 81 from the intervention group and n = 55 from the control group, who completed the 24-month follow-up. After 24 months mean body weight and body mass index were reduced significantly for completers in both groups, but almost twice as much was registered for those in the intervention group which was not significant between groups -4.4 (CI -6.1; -2.8) kg versus -2.5 (CI -3.9; -1.1) kg, P = 0.101. Haemoglobin A1c was significantly reduced in the intervention group -3.1 (CI -5.0; -1.2) mmol/mol, but not in the control group -0.2 (CI -2.4; -2.0) mmol/mol without a significant between group difference (P = 0.223). Low completion was partly due to coronavirus disease 2019. Telehealth lifestyle coaching improve long-term weight loss (> 24 months) for obese people with and without type 2 diabetes compared to usual care.

Mercury toxicokinetics--dependency on strain and gender.

Mercury (Hg) exposure from dental amalgam fillings and thimerosal in vaccines is not a major health hazard, but adverse health effects cannot be ruled out in a small and more susceptible part of the exposed population. Individual differences in toxicokinetics may explain susceptibility to mercury. Inbred, H-2-congenic A.SW and B10.S mice and their F1- and F2-hybrids were given HgCl2 with 2.0 mg Hg/L drinking water and traces of (203)Hg. Whole-body retention (WBR) was monitored until steady state after 5 weeks, when the organ Hg content was assessed. Despite similar Hg intake, A.SW males attained a 20-30% significantly higher WBR and 2- to 5-fold higher total renal Hg retention/concentration than A.SW females and B10.S mice. A selective renal Hg accumulation but of lower magnitude was seen also in B10.S males compared with females. Differences in WBR and organ Hg accumulation are therefore regulated by non-H-2 genes and gender. Lymph nodes lacked the strain- and gender-dependent Hg accumulation profile of kidney, liver and spleen. After 15 days without Hg A.SW mice showed a 4-fold higher WBR and liver Hg concentration, but 11-fold higher renal Hg concentration, showing the key role for the kidneys in explaining the slower Hg elimination in A.SW mice. The trait causing higher mercury accumulation was not dominantly inherited in the F1 hybrids. F2 mice showed a large inter-individual variation in Hg accumulation, showing that multiple genetic factors influence the Hg toxicokinetics in the mouse. The genetically heterogeneous human population may therefore show a large variation in mercury toxicokinetics.

Radiation from mobile phone systems: Is it perceived as a threat to people's health?

The aim of this study was to explore the prevalence, nature and determinants of concerns about mobile phone radiation. We used data from a 2006 telephone survey of 1004 people aged 15+ years in Denmark. Twenty-eight percent of the respondents were concerned about exposure to mobile phone radiation; radiation from masts was of concern to about 15%. In contrast, 82% were concerned about pollution. Nearly half of the respondents considered the mortality risk of 3G phones and masts to be of the same order of magnitude as being struck by lightning (0.1 fatalities per million people per year) while 7% thought it was equivalent to tobacco-induced lung cancer (approximately 500 fatalities per million per year). Among women, concerns about mobile phone radiation were positively associated with educational attainment, perceived mobile phone mortality risk and concerns about unknown consequences of new technologies. More than two thirds of the respondents felt that they had received inadequate public information about the 3G system. The results of the study indicate that the majority of the population has little concern about mobile phone radiation while a small minority is very concerned.

Impaired reproductive development in sons of women occupationally exposed to pesticides during pregnancy.

OBJECTIVES: The aim of this prospective study was to investigate whether occupational pesticide exposure during pregnancy causes adverse effects on the reproductive development in the male infants. DESIGN AND MEASUREMENTS: Pregnant women employed in greenhouses in Denmark were consecutively recruited, and 113 mother-son pairs were included. The mothers were categorized as occupationally exposed (91 sons) or unexposed (22 sons) to pesticides during pregnancy. Testicular position and volume, penile length, and position of urethral opening were determined at 3 months of age using standardized techniques. Concentrations of reproductive hormones in serum from the boys were analyzed. RESULTS: The prevalence of cryptorchidism at 3 months of age was 6.2% [95% confidence interval (CI), 3.0-12.4]. This prevalence was considerably higher than among Danish boys born in the Copenhagen area (1.9%; 95% CI, 1.2-3.0) examined by the same procedure. Boys of pesticide-exposed mothers showed decreased penile length, testicular volume, serum concentrations of testosterone, and inhibin B. Serum concentrations of sex hormone-binding globulin, follicle-stimulating hormone, and the luteinizing hormone:testosterone ratio were increased compared with boys of nonexposed mothers. For individual parameters, only the decreased penile length was statistically significant (p = 0.04). However, all observed effects were in the anticipated direction, and a joint multivariate test showed that this finding had a p-value of 0.012. CONCLUSIONS: Our findings suggest an adverse effect of maternal occupational pesticide exposure on reproductive development in the sons despite current greenhouse safeguards and special measures to protect pregnant women.

What you see may not always be what you get--bioavailability and extrapolation from in vitro tests.

In human risk assessment, bioavailability needs to be considered when relying on in vitro toxicity results. For single chemicals, this quantitative challenge is often handled through a bioavailability factor. For mixtures, however, things are more complicated. Thus, individual constituents may not only interact toxicodynamically and toxicokinetically, but the composition of constituents reaching the target site may also differ from what was present at the site of exposure due to the differences in their bioavailabilities. A recent study concluded on the in vivo potential of Australian tea-tree oil (TTO) to act as an endocrine disruptor based on an in vitro protocol measuring the growth of MCF-7 cells following chemical exposure to TTO. TTO is primarily used topically in humans, and is not a single chemical but is a mixture with some constituents penetrating the skin which others do not. The present study evaluated in an identical in vitro model to what extent TTO and its skin penetrating constituents affected the growth of MCF-7 cells. The estrogenic potency of TTO was confirmed, but none of the bioavailable TTO constituents demonstrated estrogenicity. The present study, therefore, cautions in vitro to in vivo extrapolations from the mixtures of constituents with potentially varying bioavailabilities.

Communicating effectiveness of intervention for chronic diseases: what single format can replace comprehensive information?

BACKGROUND: There is uncertainty about how GPs should convey information about treatment effectiveness to their patients in the context of cardiovascular disease. Hence we study the concordance of decisions based on one of four single information formats for treatment effectiveness with subsequent decisions based on all four formats combined with a pictorial representation. METHODS: A randomized study comprising 1,169 subjects aged 40-59 in Odense, Denmark. Subjects were randomized to receive information in terms of absolute risk reduction (ARR), relative risk reduction (RRR), number needed to treat (NNT), or prolongation of life (POL) without heart attack, and were asked whether they would consent to treatment. Subsequently the same information was conveyed with all four formats jointly accompanied by a pictorial presentation of treatment effectiveness. Again, subjects should consider consent to treatment. RESULTS: After being informed about all four formats, 52%-79% of the respondents consented to treatment, depending on level of effectiveness and initial information format. Overall, ARR gave highest concordance, 94% (95% confidence interval (91%; 97%)) between initial and final decision, but ARR was not statistically superior to the other formats. CONCLUSION: Decisions based on ARR had the best concordance with decisions based on all four formats and pictorial representation, but the difference in concordance between the four formats was small, and it is unclear whether respondents fully understood the information they received.

Laypersons' understanding of relative risk reductions: randomised cross-sectional study.

BACKGROUND: Despite increasing recognition of the importance of involving patients in decisions on preventive healthcare interventions, little is known about how well patients understand and utilise information provided on the relative benefits from these interventions. The aim of this study was to explore whether lay people can discriminate between preventive interventions when effectiveness is presented in terms of relative risk reduction (RRR), and whether such discrimination is influenced by presentation of baseline risk. METHODS: The study was a randomised cross-sectional interview survey of a representative sample (n = 1,519) of lay people with mean age 59 (range 40-98) years in Denmark. In addition to demographic information, respondents were asked to consider a hypothetical drug treatment to prevent heart attack. Its effectiveness was randomly presented as RRR of 10, 20, 30, 40, 50 or 60 percent, and half of the respondents were presented with quantitative information on the baseline risk of heart attack. The respondents had also been asked whether they were diagnosed with hypercholesterolemia or had experienced a heart attack. RESULTS: In total, 873 (58%) of the respondents consented to the hypothetical treatment. While 49% accepted the treatment when RRR = 10%, the acceptance rate was 58-60% for RRR>10. There was no significant difference in acceptance rates across respondents irrespective of whether they had been presented with quantitative information on baseline risk or not. CONCLUSION: In this study, lay people's decisions about therapy were only slightly influenced by the magnitude of the effect when it was presented in terms of RRR. The results may indicate that lay people have difficulties in discriminating between levels of effectiveness when they are presented in terms of RRR.

Dermal uptake and percutaneous penetration of organophosphate esters in a human skin ex vivo model.

Organophosphate esters (OPEs) are used as flame retardants, plasticizers, and as hydraulic fluids. They are present in indoor environments in high concentrations compared with other flame retardants, and human exposure is ubiquitous. In this study we provide data for estimating dermal uptake for eight OPEs and ranking in OPEs risk assessment. Dermal uptake and percutaneous penetration of the OPEs were studied in a Franz diffusion cell system using human skin dosed with a mixture of OPEs in an ethanol:toluene (4:1) solution. Large variation in penetration profiles was observed between the OPEs. The chlorinated OPEs tris(2-chloroisopropyl) phosphate (TCIPP), and in particular tris(2-chloroethyl) phosphate (TCEP), penetrated the skin quite rapidly while tris(1,3-dichlor-2-propyl) phosphate (TDCIPP) and triphenyl phosphate (TPHP) tended to build up in the skin tissue and only smaller amounts permeated through the skin. For tris(isobutyl) phosphate (TIBP), tris(n-butyl) phosphate (TNBP), and tris(methylphenyl) phosphate (TMPP) the mass balance was not stable over time indicating possible degradation during the experimental period of 72 h. The rates at which OPEs permeated through the skin decreased in the order TCEP > TCIPP ≥ TBOEP > TIBP ≥ TNBP > TDCIPP > TPHP > TMPP. Generally, the permeation coefficient, kp, decreased with increasing log Kow, whereas lag time and skin deposition increased with log Kow. The present data indicate that dermal uptake is a non-negligible human exposure pathway for the majority of the studied OPEs.

Natural oils affect the human skin integrity and the percutaneous penetration of benzoic acid dose-dependently.

Natural oils are extensively used in cosmetics and as treatment for a growing number of more or less specific ailments. Skin irritation and cases of allergy have repeatedly been described in the literature following exposure to these oils. The present study evaluated the extent to which three natural oils (eucalyptus oil, tea tree oil, peppermint oil) would affect the skin integrity and the percutaneous penetration of benzoic acid when applied topically in relevant concentrations. An experimental in vitro model using static diffusion cells mounted with human breast or abdominal skin was applied. The three natural oils decreased the skin integrity dose-dependently. Concomitant dermal exposure to low concentrations of peppermint oil reduced the percutaneous penetration of benzoic acid. The present study lends support to the notion that low concentrations of peppermint oil may act protective against percutaneous penetration of some chemicals, whereas higher concentrations may decrease the integrity of the dermal barrier.

Novel Pathways for Ameliorating the Fitness Cost of Gentamicin Resistant Small Colony Variants.

Small colony variants (SCVs) of the human pathogen Staphylococcus aureus are associated with persistent infections. Phenotypically, SCVs are characterized by slow growth and they can arise upon interruption of the electron transport chain that consequently reduce membrane potential and thereby limit uptake of aminoglycosides (e.g., gentamicin). In this study, we have examined the pathways by which the fitness cost of SCVs can be ameliorated. Five gentamicin resistant SCVs derived from S. aureus JE2 were independently selected on agar plates supplemented with gentamicin. The SCVs carried mutations in the menaquinone and hemin biosynthesis pathways, which caused a significant reduction in exponential growth rates relative to wild type (WT; 0.59-0.72) and reduced membrane potentials. Fifty independent lineages of the low-fitness, resistant mutants were serially passaged for up to 500 generations with or without sub-lethal concentrations of gentamicin. Amelioration of the fitness cost followed three evolutionary trajectories and was dependent on the initial mutation type (point mutation vs. deletion) and the passage condition (absence or presence of gentamicin). For SCVs evolved in the absence of gentamicin, 12 out of 15 lineages derived from SCVs with point mutations acquired intra-codonic suppressor mutations restoring membrane potential, growth rate, gentamicin susceptibility and colony size to WT levels. For the SCVs carrying deletions, all lineages enhanced fitness independent of membrane potential restoration without alterations in gentamicin resistance levels. By whole genome sequencing, we identified compensatory mutations in genes related to the σB stress response (7 out of 10 lineages). Inactivation of rpoF that encode for the alternative sigma factor SigB (σB) partially restored fitness of SCVs. For all lineages passaged in the presence of gentamicin, fitness compensation via membrane potential restoration was suppressed, however, selected for secondary mutations in fusA and SAUSA300_0749. This study is the first to describe fitness compensatory events in SCVs with deletion mutations and adaptation of SCVs to continued exposure to gentamicin.