A scaffoldless technique for self-generation of three-dimensional keratinospheroids on liquid crystal surfaces

We describe a new scaffold-free three-dimensional (3D) cell culture model using cholesteryl ester based lyotropic liquid crystal (LC) substrates. Keratinocytes were deposited randomly on the LC surface where they self-assembled into 3D microtissues or keratinospheroids. The cell density required to form spheroids was optimized. We investigated cell viability using dead/live cell assays. The adhesion characteristics of cells within the microtissues were determined using histological sectioning and immunofluorescence staining. Fourier transform infrared spectroscopy (FTIR) was used to characterize the biochemistry of the keratinospheroids. We found that both cells and microtissues could migrate on the LC surface. The viability study indicated approximately 80% viability of cells in the microtissues up to 20 days of culture. Strong intercellular adhesion was observed in the stratification of the multi-layered microspheroids using field emission-scanning electron microscopy (FE-SEM) and histochemical staining. The cytoskeleton and vinculins of the cells in the microtissues were expressed diffusely, but the microtissues were enriched with lipids and nucleic acids, which indicates close resemblance to the conditions in vivo. The basic 3D culture model based on LC may be used for cell and microtissue migration studies in response to cytochemical treatment.     

Evolution at the tip and base of the X chromosome in an African population of Drosophila melanogaster

Hitchhiking effects of advantageous mutations have been invoked to explain reduced polymorphism in regions of low crossing-over in Drosophila. Besides reducing DNA heterozygosity, hitchhiking effects should produce strong linkage disequilibrium and a frequency spectrum skewed toward an excess of rare polymorphisms (compared to the neutral expectation). We measured DNA polymorphism in a Zimbabwe population of D. melanogaster at three loci, yellow, achaete, and suppressor of forked, located in regions of reduced crossing-over. Similar to previously published surveys of these genomic regions in other populations, we observed low levels of nucleotide variability. However, the frequency spectrum was compatible with a neutral model, and there was abundant evidence for recombination in the history of the yellow and ac genes. Thus, some aspects of the data cannot be accounted for by a simple hitchhiking model. An alternative hypothesis, background selection, might be compatible with the observed patterns of linkage disequilibrium and the frequency spectrum. However, this model cannot account for the observed reduction in nucleotide heterozygosity. Thus, there is currently no satisfactory theoretical model for the data from the tip and base of the X chromosome in D. melanogaster.      

Factors influencing patient choice of dialysis versus conservative care to treat end-stage kidney disease

Background:

For every patient with chronic kidney disease who undergoes renal-replacement therapy, there is one patient who undergoes conservative management of their disease. We aimed to determine the most important characteristics of dialysis and the trade-offs patients were willing to make in choosing dialysis instead of conservative care.

Methods:

We conducted a discrete choice experiment involving adults with stage 3–5 chronic kidney disease from eight renal clinics in Australia. We assessed the influence of treatment characteristics (life expectancy, number of visits to the hospital per week, ability to travel, time spent undergoing dialysis [i.e., time spent attached to a dialysis machine per treatment, measured in hours], time of day at which treatment occurred, availability of subsidized transport and flexibility of the treatment schedule) on patients’ preferences for dialysis versus conservative care.

Results:

Of 151 patients invited to participate, 105 completed our survey. Patients were more likely to choose dialysis than conservative care if dialysis involved an increased average life expectancy (odds ratio [OR] 1.84, 95% confidence interval [CI] 1.57–2.15), if they were able to dialyse during the day or evening rather than during the day only (OR 8.95, 95% CI 4.46–17.97), and if subsidized transport was available (OR 1.55, 95% CI 1.24–1.95). Patients were less likely to choose dialysis over conservative care if an increase in the number of visits to hospital was required (OR 0.70, 95% CI 0.56–0.88) and if there were more restrictions on their ability to travel (OR = 0.47, 95%CI 0.36–0.61). Patients were willing to forgo 7 months of life expectancy to reduce the number of required visits to hospital and 15 months of life expectancy to increase their ability to travel.

Interpretation:

Patients approaching end-stage kidney disease are willing to trade considerable life expectancy to reduce the burden and restrictions imposed by dialysis.Stage 5 chronic kidney disease is a major health issue worldwide and has a mortality that exceeds many cancers.^1,2 The treatment options for stage 5 (i.e., end-stage) kidney disease include dialysis, kidney transplantation and supportive nondialytic treatment (conservative care). A national report by the Australian Institute of Health and Welfare estimates that for every patient with chronic kidney disease who undergoes dialysis or transplantation, there is one other patient whose disease is managed conservatively.³Conservative care includes the multidisciplinary management of uremic symptoms through diet and medications, such as erythropoietin and diuretics, as well as psychosocial support and eventual palliative care. The reported median survival with conservative care for end-stage kidney disease is between 6 and 32 months. For some patients, particularly the elderly and those with ischemic heart disease, this period may be equal to or greater than their expected survival with dialysis.^4–7 Dialysis usually prolongs life, but it can impose a substantial burden on patients and their families and may be associated with a reduction in quality of life. The decision to start dialysis thus involves an assessment of both the evidence-based outcomes for the population in question and the preferences of the individual patient.Incorporating patient preferences for treatment of stage 5 chronic kidney disease is recommended in clinical guidelines;⁸ however, little is known about the trade-offs that patients are willing to consider when choosing between dialysis and conservative care. Discrete choice experiments are used to quantify patient preferences. These experiments are grounded in economic theory^9,10 and allow the measurement of patients’ strengths of preferences for different characteristics of treatment and the trade-offs involved. Real-world decisions are closely simulated through the simultaneous consideration of all treatment characteristics.¹¹ Discrete choice experiments are a valid and reliable approach to eliciting preferences for health care^12–14 and have been used to measure the preferences of patients with chronic kidney disease in terms of organ donation and allocation, and end-of-life care.¹⁵Knowing patients’ preferences for the treatment of stage 5 chronic kidney disease is necessary to plan appropriate health care services and enhance the quality of care. With this study, we aimed to quantify the extent to which the characteristics of dialysis influence patient preferences for treatment and to assess the trade-offs patients were willing to make between these characteristics.     

Thermal plasticity in Drosophila melanogaster : A comparison of geographic populations

Background  

Populations of Drosophila melanogaster show differences in many morphometrical traits according to their geographic origin. Despite the widespread occurrence of these differences in more than one Drosophila species, the actual selective mechanisms controlling the genetic basis of such variation are not fully understood. Thermal selection is considered to be the most likely cause explaining these differences.     

A test of the oxidative damage hypothesis for discontinuous gas exchange in the locust Locusta migratoria

The discontinuous gas exchange cycle (DGC) is a breathing pattern displayed by many insects, characterized by periodic breath-holding and intermittently low tracheal O(2) levels. It has been hypothesized that the adaptive value of DGCs is to reduce oxidative damage, with low tracheal O(2) partial pressures (PO(2) ≈ 2-5 kPa) occurring to reduce the production of oxygen free radicals. If this is so, insects displaying DGCs should continue to actively defend a low tracheal PO(2) even when breathing higher than atmospheric levels of oxygen (hyperoxia). This behaviour has been observed in moth pupae exposed to ambient PO(2) up to 50 kPa. To test this observation in adult insects, we implanted fibre-optic oxygen optodes within the tracheal systems of adult migratory locusts Locusta migratoria exposed to normoxia, hypoxia and hyperoxia. In normoxic and hypoxic atmospheres, the minimum tracheal PO(2) that occurred during DGCs varied between 3.4 and 1.2 kPa. In hyperoxia up to 40.5 kPa, the minimum tracheal PO(2) achieved during a DGC exceeded 30 kPa, increasing with ambient levels. These results are consistent with a respiratory control mechanism that functions to satisfy O(2) requirements by maintaining PO(2) above a critical level, not defend against high levels of O(2).     

Colonization of broilers by <Emphasis Type="Italic">Campylobacter jejuni</Emphasis> internalized within <Emphasis Type="Italic">Acanthamoeba castellanii</Emphasis>

Although Campylobacter survives within amoeba in-vitro, it is unknown if intra-amoeba Campylobacter jejuni can colonize broilers. Five groups of 28 day-of-hatch chicks were placed into separate isolators. Groups (1) and (2) were challenged with page’s amoeba saline (PAS), and disinfected planktonic C. jejuni NCTC 11168, respectively. Groups (3), (4) and (5) were challenged with a C. jejuni positive control, C. jejuni in PAS, and intra-amoeba C. jejuni, respectively. After 1, 3, 7 and 14 days post challenge, seven birds from each unit were examined for C. jejuni colonization. For the first time we report that intra-amoeba C. jejuni colonized broilers.     

Comparative evaluation of the hygienic efficacy of an ultra-rapid hand dryer vs conventional warm air hand dryers

Aims: To compare an ultra‐rapid hand dryer against warm air dryers, with regard to: (A) bacterial transfer after drying and (B) the impact on bacterial numbers of rubbing hands during dryer use. Methods and Results: The Airblade? dryer (Dyson Ltd) uses two air ‘knives’ to strip water from still hands, whereas conventional dryers use warm air to evaporate moisture whilst hands are rubbed together. These approaches were compared using 14 volunteers; the Airblade? and two types of warm air dryer. In study (A), hands were contaminated by handling meat and then washed in a standardized manner. After dryer use, fingers were pressed onto foil and transfer of residual bacteria enumerated. Transfers of 0–10⁷ CFU per five fingers were observed. For a drying time of 10 s, the Airblade? led to significantly less bacterial transfer than the other dryers (P < 0·05; range 0·0003–0·0015). When the latter were used for 30–35 s, the trend was for the Airblade to still perform better, but differences were not significant (P > 0·05, range 0·1317–0·4099). In study (B), drying was performed ± hand rubbing. Contact plates enumerated bacteria transferred from palms, fingers and fingertips before and after drying. When keeping hands still, there was no statistical difference between dryers, and reduction in the numbers released was almost as high as with paper towels. Rubbing when using the warm air dryers inhibited an overall reduction in bacterial numbers on the skin (P < 0·05). Conclusions: Effective hand drying is important for reducing transfer of commensals or remaining contaminants to surfaces. Rubbing hands during warm air drying can counteract the reduction in bacterial numbers accrued during handwashing. Significance and Impact of the Study: The Airblade? was superior to the warm air dryers for reducing bacterial transfer. Its short, 10 s drying time should encourage greater compliance with hand drying and thus help reduce the spread of infectious agents via hands.