Diagnosis and Prevention of Periprosthetic Joint Infections.

The Diagnosis and Prevention of Periprosthetic Joint Infections Clinical Practice Guideline is based on a systematic review of current scientific and clinical research. Through analysis of the current best evidence, this guideline seeks to evaluate strategies to mitigate the risk of periprosthetic joint infection (PJI) in hip and knee arthroplasty and identify best practices in the diagnostic evaluation for these infections. Twenty-five recommendations related to prevention and diagnosis of PJI are presented. In addition, the work group highlighted areas for needed additional research when evidence proved lacking on the topic and carefully reviewed the rationale behind the recommendations while also noting potential harms or risks associated with implementation.

Photosynthetic heat tolerance of shade and sun leaves of three tropical tree species.

Previous studies of heat tolerance of tropical trees have focused on canopy leaves exposed to full sunlight and high temperatures. However, in lowland tropical forests with leaf area indices of 5-6, the vast majority of leaves experience varying degrees of shade and a reduced heat load compared to sun leaves. Here we tested whether heat tolerance is lower in shade than in sun leaves. For three tropical tree species, Calophyllum inophyllum, Inga spectabilis, and Ormosia macrocalyx, disks of fully developed shade and sun leaves were subjected to 15-min heat treatments, followed by measurement of chlorophyll a fluorescence after 48 h of recovery. In two of the three species, the temperature causing a 50% decrease of the fluorescence ratio Fv/Fm (T50) was significantly lower (by ~ 1.0 °C) in shade than in sun leaves, indicating a moderately decreased heat tolerance of shade leaves. In shade leaves of these two species, the rise in initial fluorescence, F0, also occurred at lower temperatures. In the third species, there was no shade-sun difference in T50. In situ measurements of photosynthetic CO2 assimilation showed that the optimum temperature for photosynthesis tended to be lower in shade leaves, although differences were not significant. At supra-optimal temperatures, photosynthesis was largely constrained by stomatal conductance, and the high-temperature CO2 compensation point, TMax, occurred at considerably lower temperatures than T50. Our study demonstrates that the temperature response of shade leaves of tropical trees differs only marginally from that of sun leaves, both in terms of heat tolerance and photosynthetic performance.

Protection by light against heat stress in leaves of tropical crassulacean acid metabolism plants containing high acid levels.

Heat tolerance of plants exhibiting crassulacean acid metabolism (CAM) was determined by exposing leaf sections to a range of temperatures both in the dark and the light, followed by measuring chlorophyll a fluorescence (Fv/Fm and F0) and assessing visible tissue damage. Three CAM species, Clusia rosea Jacq., Clusia pratensis Seem. and Agave angustifolia Haw., were studied. In acidified tissues sampled at the end of the night and exposed to elevated temperatures in the dark, the temperature that caused a 50% decline of Fv/Fm (T50), was remarkably low (40-43°C in leaves of C. rosea). Conversion of chlorophyll to pheophytin indicated irreversible tissue damage caused by malic acid released from the vacuoles. By contrast, when acidified leaves were illuminated during heat treatments, T50 was up to 50-51°C. In de-acidified samples taken at the end of the light period, T50 reached ∼54°C, irrespective of whether temperature treatments were done in the dark or light. Acclimation of A. angustifolia to elevated daytime temperatures resulted in a rise of T50 from ∼54° to ∼57°C. In the field, high tissue temperatures always occur during sun exposure. Measurements of the heat tolerance of CAM plants that use heat treatments of acidified tissue in the dark do not provide relevant information on heat tolerance in an ecological context. However, in the physiological context, such studies may provide important clues on vacuolar properties during the CAM cycle (i.e. on the temperature relationships of malic acid storage and malic acid release).

Three-Arm Randomized Phase III Trial: Quality Aloe and Placebo Cream Versus Powder as Skin Treatment During Breast Cancer Radiation Therapy.

BACKGROUND: The efficacy of aloe extract in reducing radiation-induced skin injury is controversial. The purpose of the present 3-arm randomized trial was to test the efficacy of quality-tested aloe extract in reducing the severity of radiation-induced skin injury and, secondarily, to examine the effect of a moist cream versus a dry powder skin care regimen. MATERIALS AND METHODS: A total of 248 patients with breast cancer were randomized to powder, aloe cream, or placebo cream. Acute skin toxicity was scored weekly and after treatment at weeks 1, 2, and 4 using a modified 10-point Catterall scale. The patients scored their symptom severity using a 6-point Likert scale and kept an acute phase diary. RESULTS: The aloe formulation did not reduce acute skin toxicity or symptom severity. Patients with a greater body mass index were more likely to develop acute skin toxicity. A similar pattern of increased skin reaction toxicity occurred with both study creams compared with the dry powder regimen. CONCLUSION: No evidence was found to support prophylactic application of quality aloe extract or cream to improve the symptoms or reduce the skin reaction severity. Our results support a dry skin care regimen of powder during radiation therapy.

Light-stimulated heat tolerance in leaves of two neotropical tree species, Ficus insipida and Calophyllum longifolium.

Previous heat tolerance tests of higher plants have been mostly performed with darkened leaves. However, under natural conditions, high leaf temperatures usually occur during periods of high solar radiation. In this study, we demonstrate small but significant increases in the heat tolerance of illuminated leaves. Leaf disks of mature sun leaves from two neotropical tree species, Ficus insipida Willd. and Calophyllum longifolium Willd., were subjected to 15min of heat treatment in the light (500µmol photons m-2s-1) and in the dark. Tissue temperatures were controlled by floating the disks on the surface of a water bath. PSII activity was determined 24h and 48h after heating using chlorophyll a fluorescence. Permanent tissue damage was assessed visually during long-term storage of leaf sections under dim light. In comparison to heat treatments in the dark, the critical temperature (T50) causing a 50% decline of the fluorescence ratio Fv/Fm was increased by ~1°C (from ~52.5°C to ~53.5°C) in the light. Moreover, illumination reduced the decline of Fv/Fm as temperatures approached T50. Visible tissue damage was reduced following heat treatment in the light. Experiments with attached leaves of seedlings exposed to increasing temperatures in a gas exchange cuvette also showed a positive effect of light on heat tolerance.

Thermal tolerance, net CO2 exchange and growth of a tropical tree species, Ficus insipida, cultivated at elevated daytime and nighttime temperatures.

Global warming and associated increases in the frequency and amplitude of extreme weather events, such as heat waves, may adversely affect tropical rainforest plants via significantly increased tissue temperatures. In this study, the response to two temperature regimes was assessed in seedlings of the neotropical pioneer tree species, Ficus insipida. Plants were cultivated in growth chambers at strongly elevated daytime temperature (39°C), combined with either close to natural (22°C) or elevated (32°C) nighttime temperatures. Under both growth regimes, the critical temperature for irreversible leaf damage, determined by changes in chlorophyll a fluorescence, was approximately 51°C. This is comparable to values found in F. insipida growing under natural ambient conditions and indicates a limited potential for heat tolerance acclimation of this tropical forest tree species. Yet, under high nighttime temperature, growth was strongly enhanced, accompanied by increased rates of net photosynthetic CO2 uptake and diminished temperature dependence of leaf-level dark respiration, consistent with thermal acclimation of these key physiological parameters.

Photosynthesis, photoprotection, and growth of shade-tolerant tropical tree seedlings under full sunlight.

High solar radiation in the tropics is known to cause transient reduction in photosystem II (PSII) efficiency and CO(2) assimilation in sun-exposed leaves, but little is known how these responses affect the actual growth performance of tropical plants. The present study addresses this question. Seedlings of five woody neotropical forest species were cultivated under full sunlight and shaded conditions. In full sunlight, strong photoinhibition of PSII at midday was documented for the late-successional tree species Ormosia macrocalyx and Tetragastris panamensis and the understory/forest gap species, Piper reticulatum. In leaves of O. macrocalyx, PSII inhibition was accompanied by substantial midday depression of net CO(2) assimilation. Leaves of all species had increased pools of violaxanthin-cycle pigments. Other features of photoacclimation, such as increased Chl a/b ratio and contents of lutein, ß-carotene and tocopherol varied. High light caused strong increase of tocopherol in leaves of T. panamensis and another late-successional species, Virola surinamensis. O. macrocalyx had low contents of tocopherol and UV-absorbing substances. Under full sunlight, biomass accumulation was not reduced in seedlings of T. panamensis, P. reticulatum, and V. surinamensis, but O. macrocalyx exhibited substantial growth inhibition. In the highly shade-tolerant understory species Psychotria marginata, full sunlight caused strongly reduced growth of most individuals. However, some plants showed relatively high growth rates under full sun approaching those of seedlings at 40 % ambient irradiance. It is concluded that shade-tolerant tropical tree seedlings can achieve efficient photoacclimation and high growth rates in full sunlight.

Clinical outcome of patients with diabetes presenting with ST-elevation myocardial infarction and treated with concomitant use of glycoprotein IIb/IIIa inhibitors.

BACKGROUND: Percutaneous coronary intervention (PCI) with stent implantation is considered to be the standard treatment in patients presenting with ST-elevation myocardial infarction (STEMI). According to the American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for STEMI, there is a class IIa recommendation (treatment reasonable) for platelet glycoprotein (GP) IIb/IIIa inhibitors. This study aims to compare the clinical outcome of patients with and without diabetes, presenting with STEMI undergoing primary PCI with concomitant usage of GP IIb/IIIa inhibitors in real clinical practice. METHODS: Over the course of three years (2004-2006) 394 consecutive patients presenting with STEMI were included in this single centre experience. There were 95 patients (24%) with, and 299 patients (76%) without, diabetes. A GP IIb/IIIa inhibitor was administered to all patients without contraindications (316 patients, 80%). RESULTS: Patients with diabetes were significantly older, more often suffered from hypertension and had a higher incidence of obesity. The rate of administration of GP IIb/IIIa inhibitors was similar in both groups (74% vs. 82%, p = 0.14). The in-hospital incidence of major adverse cardiac events (MACE, defined as death, re-myocardial infarction, target lesion revascularisation and coronary artery bypass graft) was similar in both patient groups (18 [19%] diabetics vs. 51 [17%] non-diabetics, p = 0.65). Hypertension, age and obesity were identified as predictors for MACE, whereas diabetes was not predictive. CONCLUSIONS: In this single centre experience, in diabetic and non-diabetic patients presenting with STEMI, combination therapy with primary PCI and GP IIb/IIIa inhibitors might have contributed to a similar clinical outcome.

Direct versus conventional stent implantation in patients with acute coronary syndrome just before the era of drug-eluting stents.

BACKGROUND: Direct stent implantation in patients, who undergo elective percutaneous coronary intervention (PCI) can be performed with a high success rate and clinical results that are comparable to those after predilatation. It was the aim of this prospective study to compare clinical, angiographic and procedural parameter of direct stent implantation (DS) and conventional stent implantation (CS) in patients with acute coronary syndrome (ACS). PATIENTS AND METHODS: We analysed 194 patients with ACS (ST-elevation myocardial infarction 66%, non-ST-elevation myocardial infarction 18%, unstable angina 16%), in whom primary PCI was performed between January and December 2002. In 156 (80%) patients glycoprotein IIb/IIIa inhibitors were administered during the procedure. In 73 patients (38%) direct stent implantation could be performed successfully. In 12 patients (6%) direct stent implantation failed due to the inability to pass the stenosis. In 121 patients (62%) the stent was implanted after predilatation. RESULTS: The clinical parameters were comparable in both groups. Reference luminal diameter before stent implantation did not differ in both groups (DS 3.01+/-0.54 vs. CS 2.84+/-0.43 mm). The final minimal luminal diameter was significantly higher in the DS group (DS 2.95+/-0.45 vs. CS 2.77+/-0.47 mm, p=0.01). The procedural time (DS 41.0+/-14.1 vs. CS 46.8+/-16.9 min, p=0.02), radiation exposure time (DS 7.3+/-4.6 vs. CS 8.9+/-4.6 min, p=0.002) and the amount of contrast agent (DS 216+/-90 vs. CS 235+/-79 ml, p=0.03) could be decreased by the technique of direct stent implantation. The incidence of major adverse cardiac events (death, myocardial infarction, CABG) during hospitalization was 4.1% in the DS group and 11.5% in the CS group (p=0.11). CONCLUSIONS: Direct stent implantation is safe and feasible in patients with acute coronary syndromes. The procedural time, radiation exposure time and the amount of contrast agent can be significantly decreased using the technique of direct stent implantation. The incidence of major adverse cardiac events was not significantly different in this subset of patients.