Nasal Screening for MRSA: Different Swabs – Different Results!

Objectives

Swab-based nasal screening is commonly used to identify asymptomatic carriage of Staphylococcus aureus in patients. Bacterial detection depends on the uptake and release capacities of the swabs and on the swabbing technique itself. This study investigates the performance of different swab-types in nasal MRSA-screening by utilizing a unique artificial nose model to provide realistic and standardized screening conditions.

Methods

An anatomically correct artificial nose model was inoculated with a numerically defined mixture of MRSA and Staphylococcus epidermidis bacteria at quantities of 4×10² and 8×10² colony forming units (CFU), respectively. Five swab-types were tested following a strict protocol. Bacterial recovery was measured for direct plating and after elution into Amies medium by standard viable count techniques.

Results

Mean recovered bacteria quantities varied between 209 and 0 CFU for MRSA, and 365 and 0 CFU for S. epidermidis, resulting swab-type-dependent MRSA-screening-sensitivities ranged between 0 and 100%. Swabs with nylon flocked tips or cellular foam tips performed significantly better compared to conventional rayon swabs referring to the recovered bacterial yield (p<0.001). Best results were obtained by using a flocked swab in combination with Amies preservation medium. Within the range of the utilized bacterial concentrations, recovery ratios for the particular swab-types were independent of the bacterial species.

Conclusions

This study combines a realistic model of a human nose with standardized laboratory conditions to analyze swab-performance in MRSA-screening situations. Therefore, influences by inter-individual anatomical differences as well as diverse colonization densities in patients could be excluded. Recovery rates vary significantly between different swab-types. The choice of the swab has a great impact on the laboratory result. In fact, the swab-type contributes significantly to true positive or false negative detection of nasal MRSA carriage. These findings should be considered when screening a patient.     

Variation in Trill Characteristics in Tree Pipit Songs: Different Trills for Different Use?

Transmitting information about singer's quality is an important function of song in many bird species, and this information should be useful in territorial interactions. Fast trills, being physically demanding song structures, are particularly suitable candidates for signalling of quality or aggressive motivation. We have evaluated trill characteristics in songs within a population of the Tree Pipit, a common European songbird with no sexual dimorphism, in which song apparently plays a key role in territory defence as well as mate choice. Two types of relatively fast trills (each of them in multiple variants differing in complexity) were commonly observed in repertoires of Tree Pipit males. Trill rates significantly differed among individuals, suggesting that these song structures may carry information about male quality in this species. We tested by playback experiments whether both trill types are used in territorial encounters. Only one of the trill types was sung by males in response to playback, regardless on the trill type played to them. In an immediate response to playback, they increased the frequency of use of this trill, and also significantly increased the trill rate in comparison with spontaneous songs. This confirmed field observations, suggesting that this trill is important in male–male interactions. On the contrary, the use of the fastest, apparently more demanding, trill type actually decreased after the simulated territorial intrusion. We hypothesize that the latter one is more directed towards females, and that while performance of both trill types may reflect male quality, they are primarily used in different contexts.     

Different ζ globin gene deletions among Black Americans

Summary Four types of chromosomes with a deletion between the human embryonic and globin genes were identified among 2.8% of 321 Black Americans from Georgia. Two deletions of approximately 11 kb which differed by about 300 bp occurred on chromosomes with or without a polymorphic Xba I site 5 to the globin gene [(X⁺) or (X^-)]. The deletions are identifiable in Xba I digests of genomic DNA using an or a globin gene probe which yield fragments of 23 kb from (X⁺)–^* chromosomes or 27 kb from (X^–)–^* chromosomes. Digestion with other enzymes and probing with both and probes gave fragments typical of the two globin gene deletions previously identified in Polynesians. Among Black Americans, these globin gene deletions have been found in combination with globin gene deletions in trans but not in cis. Homozygotes have not been found. Hematologic data on carriers of the globin gene deletions in association with Hb AS, SS, and SC suggest that these deletions have no effect on the function of the adult globin genes.     

Leghemoglobin: Different roles for different components?

The ratio of leghemoglobin c content to leghemoglobin a content in soybean (Glycine max) root nodules drops in the early stages of plant growth and becomes constant during flowering and fruiting. These data bring into question the assumption that leghemoglobin components have a single biochemical role in nitrogen fixation.     

Sulfur Metabolism in Plants: Are Trees Different?

Sulfur metabolite levels and sulfur metabolism have been studied in a significant number of herbaceous and woody plant species. However, only a limited number of datasets are comparable and can be used to identify similarities and differences between these two groups of plants. From these data, it appears that large differences in sulfur metabolite levels, as well as the genetic organization of sulfate assimilation and metabolism do not exist between herbaceous plants and trees. The general response of sulfur metabolism to internal and/or external stimuli, such as oxidative stress, seems to be conserved between the two groups of plants. Thus, it can be expected that, generally, the molecular mechanisms of regulation of sulfur metabolism will also be similar. However, significant differences have been found in fine tuning of the regulation of sulfur metabolism and in developmental regulation of sulfur metabolite levels. It seems that the homeostasis of sulfur metabolism in trees is more robust than in herbaceous plants and a greater change in conditions is necessary to initiate a response in trees. This view is consistent with the requirement for highly flexible defence strategies in woody plant species as a consequence of longevity. In addition, seasonal growth of perennial plants exerts changes in sulfur metabolite levels and regulation that currently are not understood. In this review, similarities and differences in sulfur metabolite levels, sulfur assimilation and its regulation are characterized and future areas of research are identified.     

Are Standard Intra-Abdominal Pressure Values Different during Pregnancy?

Background

Measurement of intra-abdominal pressure (IAP) is an important parameter in the surveillance of intensive care unit patients. Standard values of IAP during pregnancy have not been well defined. The aim of this study was to assess IAP values in pregnant women before and after cesarean delivery.

Methods

This prospective study, carried out from January to December 2011 in a French tertiary care centre, included women with an uneventful pregnancy undergoing elective cesarean delivery at term. IAP was measured through a Foley catheter inserted in the bladder under spinal anaesthesia before cesarean delivery, and every 30 minutes during the first two hours in the immediate postoperative period.

Results

The study included 70 women. Mean IAP before cesarean delivery was 14.2 mmHg (95%CI: 6.3–23). This value was significantly higher than in the postoperative period: 11.5 mmHg (95%CI: 5–19.7) for the first measurement (p = 0.002). IAP did not significantly change during the following two postoperative hours (p = 0.2). Obese patients (n = 25) had a preoperative IAP value significantly higher than non-obese patients: 15.7 vs. 12.4; p = 0.02.

Conclusion

In term pregnancies, IAP values are significantly higher before delivery than in the post-partum period, where IAP values remain elevated for at least two hours at the level of postoperative classical abdominal surgery. The knowledge of these physiological changes in IAP values may help prevent organ dysfunction/failure when abdominal compartment syndrome occurs after cesarean delivery.     

Do the Preferences of Healthcare Provider Selection Vary among Rural and Urban Patients with Different Income and Cause Different Outcome?

BackgroundEqual access to healthcare facilities and high-level quality of care are important strategies to eliminate the disparity in outcome of care. However, the existing literature regarding how urban or rural dwelling patients with different income level select healthcare providers is insufficient. The purposes of this study were to examine whether differences of healthcare provider selection exist among urban and rural coronary artery bypass surgery (CABG) patients with different income level. If so, we further investigated the associated impact on mortality.MethodsA retrospective, multilevel study design was conducted using claims data from 2007–2011 Taiwan’s Universal Health Insurance Scheme. Healthcare providers’ performance and patients’ travelling distance to hospitals were used to define the patterns of healthcare provider selection. Baron and Kenny’s procedures for mediation effect were conducted.ResultsThere were 10,108 CABG surgeries included in this study. The results showed that urban dwelling and higher income patients were prone to receive care from better-performance providers. The travelling distances of urban dwelling patients was 15 KM shorter, especially when they received better-performance provider’s care. The results also showed that the difference of healthcare provider selection and mortality rate existed between rural and urban dwelling patients with different income levels. After the procedure of mediation effect testing, the results showed that the healthcare provider selection partially mediated the relationships between patients’ residential areas with different income levels and 30-day mortality.ConclusionPreferences of healthcare provider selection vary among rural and urban patients with different income, and such differences partially mediated the outcome of care. Health authorities should pay attention to this issue, and propose appropriate solutions to eliminate the disparity in outcome of CABG care.     

Is Autonomic Modulation Different between European and Chinese Astronauts?

Purpose

The objective was to investigate autonomic control in groups of European and Chinese astronauts and to identify similarities and differences.

Methods

Beat-to-beat heart rate and finger blood pressure, brachial blood pressure, and respiratory frequency were measured from 10 astronauts (five European taking part in three different space missions and five Chinese astronauts taking part in two different space missions). Data recording was performed in the supine and standing positions at least 10 days before launch, and 1, 3, and 10 days after return. Cross-correlation analysis of heart rate and systolic pressure was used to assess cardiac baroreflex modulation. A fixed breathing protocol was performed to measure respiratory sinus arrhythmia and low-frequency power of systolic blood pressure variability.

Results

Although baseline cardiovascular parameters before spaceflight were similar in all astronauts in the supine position, a significant increase in sympathetic activity and a decrease in vagal modulation occurred in the European astronauts when standing; spaceflight resulted in a remarkable vagal decrease in European astronauts only. Similar baseline supine and standing values for heart rate, mean arterial pressure, and respiratory frequency were shown in both groups. Standing autonomic control was based on a balance of higher vagal and sympathetic modulation in European astronauts.

Conclusion

Post-spaceflight orthostatic tachycardia was observed in all European astronauts, whereas post-spaceflight orthostatic tachycardia was significantly reduced in Chinese astronauts. The basis for orthostatic intolerance is not apparent; however, many possibilities can be considered and need to be further investigated, such as genetic diversities between races, astronaut selection, training, and nutrition, etc.     

Cell and Solution Velocity Constants for the Reaction CO + Hb → COHb at Different Temperatures in Mammals with Different Red Cell Sizes

Using a double beam stopped-flow apparatus, measurements were made of the velocity constant of the reaction CO + Hb → COHb in solution and in the red cells of human beings, rabbits, horses, and goats. The solution constant (l'') at 37°C for human beings was 362 mM ^-1 sec.^-1; in other species l'' was somewhat lower. Two rabbits, despite having apparently identical hemoglobins had significantly different values for l''. The energy of activation (E) of l'' was between 8 and 11 kcal/mole in all cases. The cell reaction constant (l''_c) at 37° was between 61 and 73 mM ^-1 sec.^-1 in all cases; at 37° the trend was for the smaller cells to have the higher l''_c. This cell size effect was much less than previously found for the faster oxygen reaction. This showed that by merely increasing the rate of chemical reaction, it was not possible to increase cell uptake rate beyond a certain level, this level being dependent on the size and membrane properties of the cell. At lower temperatures l'' was a more important factor in determining l''_c than was cell size. The cell membrane was a barrier to gas diffusion in all species. The effect of temperature on l''_c was also measured and was less than its effect on l'' at most temperatures. Temperature effect increased in small cells at low temperatures. Both these findings are in accordance with predictions based on differentiation of Roughton''s equations.     

Different dimerisation mode for TLR4 upon endosomal acidification?

TLR4 is unique among pathogen-recognition receptors in that it initiates different pathways in different cellular locations. Binding of a bridging factor, Mal, allows recruitment of an adapter protein, MyD88, at the plasma membrane, which leads to the production of proinflammatory cytokines. Upon internalization, TLR4 uses a different bridging factor, TRAM, to activate a MyD88-independent pathway that results in type I interferon expression. Interestingly, both Mal and TRAM are localised initially at the plasma membrane. In this Opinion, I suggest a possible mechanism by which endosomal acidification triggers the differential adaptor usage of TLR4. I discuss the evidence of the pH sensitivity of TLR4 and propose a new dimerisation mode for TLR4 based on the crystal structure of the related receptor TLR3 bound to its ligand, double-stranded RNA.     

Different fates of mitochondria: alternative ways for degradation?

Cellular degradative processes including proteasomal and vacuolar/lysosomal (autophagic) degradation, as well as the activity of proteases (both cytosolic and mitochondrial), provide for a continuous turnover of damaged and obsolete macromolecules and organelles. Mitochondria are organelles essential for respiration and oxidative energy production in aerobic cells; they are also required for multiple biosynthetic pathways. As such, mitochondrial homeostasis is very important for cell survival. We review the evidence regarding the possible mechanisms for mitochondrial degradation. Increasingly, the evidence suggests autophagy plays a central role in the degradation of mitochondria. How mitochondria might be specifically selected for autophagy (mitophagy) remains an open question, although some evidence suggests that, under certain circumstances, in mammalian cells the Mitochondrial Permeability Transition (MPT) plays a role in initiation of the process. As more is learned about the functioning of autophagy as a degradation process, the greater the appreciation we are developing concerning its role in the control of mitochondrial degradation.     

Different evolution rates within the lens-specificβ-crystallin gene family

Summary We have determined the sequence of a rat A3/A1-crystallin complementary DNA (cDNA) clone and the (partial) sequence of the human B3-crystallin gene. Calculation of the ratio of silent to nonsynonymous substitution between orthologous A3/A1-, B3-, and other - and -crystallin sequences revealed that the region encoding the two globular domains of the A3/A1-crystallin sequence is the best conserved during evolution, much better than the corresponding region of the B1-, B3-, or the -crystallin sequences, and even better (at least in the rodent/frog comparison) that the well-conserved A-crystallin sequence. Remarkably, the rate of change of the A3/A1-crystallin coding sequence does not differ in the rodent and primate lineages, in contrast with previous findings concerning the evolution rates of the A- or -crystallin sequences in these two lineages. Comparison of the regions that encode the four motifs of the -crystallin between orthologous mammalian sequences showed that the extent of nonsynonymous substitution in each of these four homologous motif regions is the same. However, when the orthologous -crystallin genes of more distantly related species (mammals vs chicken or frog) are compared, the extent of nonsynonymous substitution is higher in the regions encoding the external motifs I and III than in the regions encoding the internal motifs II and IV. This phenomenon is also observed when paralogous members of the /-crystallin supergene family are compared.     

Ciliary and Nuclear Transport: Different Places,Similar Routes?

Cilia and flagella are membrane-sheathed, microtubule-based protrusions that decorate the surface of many eukaryotic cells. At their base, they form a selective barrier that concentrates certain proteins within the cilia but excludes others. Kee et al. (2012) now propose that nuclear pore complex proteins form a fundamental part of this diffusion barrier.     

Different strokes: Can managing behavioral types increase post-release success?

Re-introduction programs for endangered animals operate under the hope that protected habitats can sustain viable populations that rely little on humans. The goal of these programs is to supply animals with the resources and skills they need to succeed in the modern wild. However, predicting the set of skills necessary to respond to unpredictable selection events is difficult and efforts sometimes fail as animals respond inappropriately to environmental variation because they lack behavioral flexibility. Population resilience to environmental change may be enhanced if all members of a population do not exhibit the same response when selection pressures change. In many species individual animals express behavioral types that exhibit alternative responses to the same stimuli. Yet when animals are prepared for release to the wild, there is rarely consideration of consistent behavioral variation between individuals. Since experience influences both behavioral and physiological responses to varied stimuli and can shape the future behavioral type of captive animals, pre-release environmental enrichment may be successful in facilitating the expression of varied behavioral types in populations slated for release. This approach to environmental enrichment requires a departure from a ‘one size fits all’ strategy and may also involve exposure to increased challenge and competition. In addition, there is a need for empirical evidence to better understand the role of environmental enrichment and behavioral types on post-release success. The zoo environment provides an excellent arena for examining the development and expression of behavioral types and for taking a novel functional approach to environmental enrichment research that may prove to be very important to re-introduction efforts.     

Developmental Evolution: Torso — a Story with Different Ends?

The Torso pathway patterns the ends of the Drosophila embryo. Now, it has been found to control axis elongation in the short germ insect Tribolium. This result raises the issue of the ancestral function of the Torso pathway and its evolution.     

Inhibition Kinetics and the Aggregation of α-Glucosidase by Different Denaturants

Kinetic changes of alpha-glucosidase from Saccharomyces cerevisiae in guanidinium chloride (GdmCl) and SDS solutions were investigated. The results showed both denaturants can lead conformational changes and loss of enzymatic activities. However, the concentrations of denaturants causing loss of activities were much lower than that of conformational changes, which suggested that the conformation of active site of α-glucosidase was more fragile than the whole molecular conformation in response to the two denaturants. According to the different kinetic process of the enzyme in the GdmCl and SDS solutions, the further investigation on the process of denaturation were made, it showed GdmCl and SDS had different types of inhibition and different types of interaction with the enzyme. Furthermore, the mechanisms of the two denaturants were discussed.     

Comparative Evaluation of α-Amylase Refolding Through Two Different Artificial Chaperone Systems

Two different artificial chaperone systems were evaluated in this work using either detergents or CDs as the stripping agents. Upon dilution of urea-denatured α-amylase to a non-denaturing urea concentration in the presence of the capturing agent, complexes of the detergent and non-native protein molecules are formed and thereby the formation of protein aggregates is prevented. The so-called captured protein is unable to refold from the detergent-protein complex states unless a stripping agent is used to remove the detergent molecules. Our results by fluorescence, UV, turbidity measurement, circular dichroism, surface tension and activity assay indicated that the extent of refolding assistance was different due to different inter- and intra- molecular interactions in the two different systems. However, the high activity recovery in the presence of detergents, as the stripping agent, suggests that they can constitute suitable replacement for the more expensive and common stripping agent of cyclodextrins.