The CoPhyLab comet-simulation chamber

The Comet Physics Laboratory (CoPhyLab) is an international research program to study the physical properties of cometary analog materials under simulated space conditions. The project is dedicated to studying, with the help of multiple instruments and the different expertise and background from the different partners, the physics of comets, including the processes inside cometary nuclei, the activity leading to the ejection of dust and gas, and the sub-surface and surface evolution of cometary nuclei when exposed to solar illumination. CoPhyLab will provide essential information on the formation and evolution of comets and insights into the origins of primitive Solar System bodies. To this end, we constructed a new laboratory that hosts several small-scale experiments and a large-scale comet-simulation chamber (L-Chamber). This chamber has been designed and constructed to host ice-dust samples with a diameter of up to 250 mm and a variable height between 100 and 300 mm. The cometary-analog samples will be kept at temperatures below 120 K and pressures around 10^-6 mbar to ensure cometary-like conditions. In total, 14 different scientific instruments are attached to the L-Chamber to study the temporal evolution of the physical properties of the sample under different insolation conditions. Due to the implementation of a scale inside the L-Chamber that can measure weight changes of the samples with high precision, the cooling system is mechanically decoupled from the sample holder and cooling of the samples occurs by radiation only. The constructed chamber allows us to conduct uninterrupted experiments at low temperatures and pressures up to several weeks.

A prospective RCT comparing combined chromoendoscopy with water exchange (CWE) vs water exchange (WE) vs air insufflation (AI) in adenoma detection in screening colonoscopy

Background

A low adenoma detection rate (ADR) increases risks of interval cancers (ICs). Proximal colon flat polyps, e.g. serrated lesions (SLs), are difficult to find. Missed proximal colon flat lesions likely contribute to IC.

Aims

We compared chromoendoscopy with water exchange (CWE), water exchange (WE) and air insufflation (AI) in detecting adenomas in screening colonoscopy.

Methods

After split-dose preparation, 480 veterans were randomized to AI, WE and CWE.

Results

Primary outcome of proximal ADR (55.6% vs 53.4% vs 52.2%, respectively) were similar in all groups. Adenoma per colonoscopy (APC) and adenoma per positive colonoscopy (APPC) were comparable. Detection rate of proximal colon SLs was significantly higher for CWE and WE than AI (26.3%, 23.6% and 11.3%, respectively, p = 0.002). Limitations: single operator; SLs only surrogate markers of but not IC.

Conclusions

When an endoscopist achieves high-quality AI examinations with overall ADR twice (61.6%) the recommended standard (30%), use of WE and CWE does not produce further improvement in proximal or overall ADR. Comparable APC and APPC confirm equivalent withdrawal inspection techniques. WE alone is sufficient to significantly improve detection of proximal SLs. The impact of increased detection of proximal SLs by WE on prevention of IC deserves to be studied. This study is registered at ClinicalTrial.gov (NCT#01607255).

[Impact of quality improvement process upon the state of nutritional support in a critical care unit]

INTRODUCTION

In a preceding article the state of Nutritional support (NS) in an Intensive Care Unit (ICU) was documented [Martinuzzi A et al. Estado del soporte nutricional en una unidad de Cuidados críticos. RNC 2011; 20: 5-17]. In this follow-up work we set to assess the impact of several organizational, recording and educational interventions upon the current state of NS processes.

MATERIALS AND METHODS

Interventions comprised presentation of the results of the audit conducted at the ICU before the institution's medical as well as paramedical personnel; their publication in a periodical, peer-reviewed journal; drafting and implementation of a protocol regulating NS schemes to be carried out at the ICU; and conduction of continuous education activities on Nutrition (such as "experts talks", interactive courses, and training in the implementation of the NS protocol). The state of NS processes documented after the interventions was compared with the results annotated in the preceding article. Study observation window ran between March the 1st, 2011 and May 31th, 2011, both included.

RESULTS

Study series differed only regarding overall-mortality: Phase 1: 40.0% vs. Phase 2: 20.5%; Difference: 19.5%; Z = 1.927; two-tailed-p = 0.054. Interventions resulted in a higher fulfillment rate of the prescribed NS indication; an increase in the number of patients receiving ≥ 80% of prescribed energy; and a reduction in the number of NS lost days. Mortality was (numerically) lower in patients in which the prescribed NS scheme was fulfilled, NS was early initiated, and whom received ≥ 80% of prescribed energy. Adopted interventions had no effect upon average energy intakes: Phase 1: 574.7 ± 395.3 kcal/24 h⁻¹ vs. Phase 2: 591.1 ± 315.3 kcal/24 h⁻¹; two-tailed-p > 0.05.

CONCLUSIONS

Educational, recording and organizational interventions might result in a better conduction of NS processes, and thus, in a lower mortality. Hemodynamic instability is still the most formidable obstacle for initiating and completing NS.

Pattern formation in auxin flux

The plant hormone auxin is fundamental for plant growth, and its spatial distribution in plant tissues is critical for plant morphogenesis. We consider a leading model of the polar auxin flux, and study in full detail the stability of the possible equilibrium configurations. We show that the critical states of the auxin transport process are composed of basic building blocks, which are isolated in a background of auxin depleted cells, and are not geometrically regular in general. The same model was considered recently through a continuous limit and a coupling to the von Karman equations, to model the interplay of biochemistry and mechanics during plant growth. Our conclusions might be of interest in this setting, since, for example, we establish the existence of Lyapunov functions for the auxin flux, proving in this way the convergence of pure transport processes toward the set of equilibrium points.

Historical advances in the study of global terrestrial soil organic carbon sequestration

This paper serves two purposes: it provides a summarized scientific history of carbon sequestration in relation to the soil-plant system and gives a commentary on organic wastes and SOC sequestration. The concept of soil organic carbon (SOC) sequestration has its roots in: (i) the experimental work of Lundegårdh, particularly his in situ measurements of CO2 fluxes at the soil-plant interface (1924, 1927, 1930); (ii) the first estimates of SOC stocks at the global level made by Waksman [Waksman, S.A., 1938. Humus. Origin, Chemical Composition and Importance in Nature, second ed. revised. Williams and Wilkins, Baltimore, p. 526] and Rubey [Rubey, W.W., 1951. Geologic history of sea water. Bulletin of the Geological Society of America 62, 1111-1148]; (iii) the need for models dealing with soil organic matter (SOM) or SOC dynamics beginning with a conceptual SOM model by De Saussure (1780-1796) followed by the mathematical models of Jenny [Jenny, H., 1941. Factors of Soil Formation: a System of Quantitative Pedology. Dover Publications, New York, p. 288], Hénin and Dupuis [Hénin, S., Dupuis, M., 1945. Essai de bilan de la matière organique. Annales d'Agronomie 15, 17-29] and more recently the RothC [Jenkinson, D.S., Rayner, J.H., 1977. The turnover of soil organic matter in some of the Rothamsted classical experiments. Soil Science 123 (5), 298-305] and Century [Parton, W.J., Schimel, D.S., Cole, C.V., Ojima, D.S., 1987. Analysis of factors controlling soil organic matter levels in great plains grasslands. Soil Science Society of America Journal 51 (5), 1173-1179] models. The establishment of a soil C sequestration balance is not straightforward and depends greatly on the origin and the composition of organic matter that is to be returned to the system. Wastes, which are important sources of organic carbon for soils, are taken as an example. For these organic materials the following factors have to be considered: the presence or absence of fossil C, the potential of direct and indirect emissions of non-CO2 greenhouse gases (CH4 and N2O) following application and the agro-system which is being used as a comparative reference.

Problem-solving strategies in dementia patient-caregiver dyads

Examined was the applicability of concepts of the zone of proximal development and scaffolding to the study of dementia. Caregiver-patient dyads were compared to normal elderly dyads in the instructional strategies they used to complete the Block Design subtest of the WAIS-R. Shown by the results was that the use of a detailed behavioral coding scheme was successful in documenting systematic differences between the two groups. Potential use in assessment and intervention is discussed.

Effects of an acute bacterial infection on serum thyroid hormones and nuclear triiodothyronine receptors in mice

Serum T3, T4, and rT3 levels as well as liver nuclear T3 receptors (NT3R) were measured in mice with a bacterial infection. Pseudomonas aeruginosa were injected into one thigh of ICR mice, resulting in a severe infection at sacrifice 15 h later. Since food intake, which influences serum thyroid hormone levels and NT3R, was 75% lower in infected than in control mice, infected mice were either fed and compared with pair-fed controls or fasted and compared with fasted and fed controls. Fasting induced a fall in serum T3 and T4 levels, which was even more pronounced in infected fasted animals. However, while fasting caused an approximately 80% increase in serum rT3 concentrations, serum rT3 levels in infected fasted animals were not different from those in fed controls. The combination of infection and fasting thus prevented the rise in serum rT3 otherwise invariably associated with fasting. NT3R measurements on isolated nuclei revealed the presence of NT3R in mouse liver similar to those reported in rat liver. The NT3R Kd (approximately 2 X 10(-10) M) was not affected by decreased food intake, infection, or a combination thereof. The NT3R maximum binding capacity (MBC) was decreased in fasted animals (460 vs. 306 pg/mg DNA). However, the MBC of infected fasted mice was not different from that of fasted mice. Similarly, no difference in MBC was found between infected fed and pair-fed control mice. In mice injected with heat-killed P. aeruginosa to evaluate potential effects of endotoxins, neither serum thyroid hormone levels nor hepatic NT3R were different from those of controls. These data show that in mice, a severe bacterial infection with P. aeruginosa has effects on serum hormone levels not explained by the disease-associated diminished food intake, whereas it has no effects on liver NT3R beyond those due to the disease-related decreased food intake.

Antibiotic therapy of infections due to Pseudomonas aeruginosa in normal and granulocytopenic mice: comparison of murine and human pharmacokinetics

An effort was made to elucidate the limits of drug-activity tests in small animals. Human plasma kinetics of gentamicin, netilmicin, ticarcillin, ceftazidime, and ceftriaxone were approximated in normal and in granulocytopenic mice infected with various strains of Pseudomonas aeruginosa in the thigh muscle or intraperitoneally. The effect of such dosing on bacterial time-kill curves and on survival was compared with the effect of identical amounts of drug given as a single-bolus injection. With beta-lactams, a highly significant superiority of fractionated dosing (simulated human kinetics) over bolus injections (murine plasma kinetics) was demonstrated, whereas with aminoglycosides it was a single-bolus injection that tended to be more active. Thus, when tested in conventional small-animal models, aminoglycoside activity may be overestimated, whereas beta-lactam activity may be underestimated in respect to humans. These differences found in vivo most probably reflect the different pharmacodynamics between aminoglycosides and beta-lactam drugs (time-kill curves, dose-response curves, and postantibiotic effect) similar to those previously observed in vitro.

Impact of dosing intervals on activity of gentamicin and ticarcillin against Pseudomonas aeruginosa in granulocytopenic mice

The influence of dosing intervals on the activity of gentamicin and ticarcillin against Pseudomonas aeruginosa was studied in vivo. Granulocytopenic mice infected with P. aeruginosa in the thigh muscle were treated with 1-hr or 3-hr injections of gentamicin, ticarcillin, or gentamicin-ticarcillin. Plasma pharmacokinetics of the drugs were correlated with antibacterial activity. Gentamicin injected every 1 hr tended to be less active than gentamicin injected at longer intervals. In contrast, ticarcillin given every 1 hr was significantly more efficacious than equivalent total doses injected every 3 hr. The dosing schedule of gentamicin-ticarcillin was again important for ticarcillin but did not appreciably affect the antibacterial activity of gentamicin. Thus, antimicrobial chemotherapy of P. aeruginosa infections in the granulocytopenic host might be improved by administering ticarcillin rather than gentamicin as a constant infusion.

The effect of prostaglandin F2alpha on corpus luteal function in the rhesus monkey

An experimental model was set up to show whether PGF2alpha caused luteolysis when adequate chorionic gonadotropin was administered. Four mature female rhesus monkeys were studied for two cycles each. HCG was given after ovulation until day 36. PGF2alpha was given on days 28 and 29 in one cycle, while the other served as control. In five out of the total eight cycles studied, the luteal function was maintained up to day 36. However, gradual decline of serum progesterone was noted after days 22 to 26 despite the continuous administration of hCG. Administration of PGF2alpha on days 28 and 29 did not accelerate CL regression. It was also noted that hCG in doses of 500 IU did not maintain CL function in three of four cycles when surgical stress was added.