Home About us Contact
|
Home About us Contact | ||
|
|
||
Mean Rate (mean + rate)
Selected AbstractsREDUCTIONS IN OXYGEN CONSUMPTION DURING DIVES AND ESTIMATED SUBMERGENCE LIMITATIONS OF STELLER SEA LIONS (EUMETOPIAS JUBATUS)MARINE MAMMAL SCIENCE, Issue 2 2007Gordon D. Hastie Abstract Accurate estimates of diving metabolic rate are central to assessing the energy needs of marine mammals. To circumvent some of the limitations inherent with conducting energy studies in both the wild and captivity, we measured diving oxygen consumption of two trained Steller sea lions (Eumetopias jubatus) in the open ocean. The animals dived to predetermined depths (5,30 m) for controlled periods of time (50,200 s). Rates of oxygen consumption were measured using open-circuit respirometry before and after each dive. Mean resting rates of oxygen consumption prior to the dives were 1.34 (±0.18) and 1.95 (±0.19) liter/min for individual sea lions. Mean rates of oxygen consumption during the dives were 0.71 (±0.24) and 1.10 (±0.39) liter/min, respectively. Overall, rates of oxygen consumption during dives were significantly lower (45% and 41%) than the corresponding rates measured before dives. These results provide the first estimates of diving oxygen consumption rate for Steller sea lions and show that this species can exhibit a marked decrease in oxygen consumption relative to surface rates while submerged. This has important consequences in the evaluation of physiological limitations associated with diving such as dive duration and subsequent interpretations of diving behavior in the wild. [source] An additional phase in PCr use during sustained isometric exercise at 30% MVC in the tibialis anterior muscleNMR IN BIOMEDICINE, Issue 4 2002C. J. Houtman Abstract The occurrence of an abrupt acceleration in phosphocreatine hydrolysis in the tibial anterior muscle during the last part of a sustained isometric exercise at 30% maximal voluntary contraction until fatigue is demonstrated in seven out of eight healthy subjects by applying in vivo31P NMR spectroscopy at 1.5,T field strength. This additional third phase in PCr hydrolysis, is preceded by a common biphasic pattern (first fast then slow) in PCr use. The NMR spectra, as localized by a surface coil and improved by proton irradiation, were collected at a time resolution of 16 s. Mean rates of PCr hydrolysis during exercise were ,0.44,±,0.19% s,1, ,0.07,±,0.04% s,1, and ,0.29,±,0.10% s,1 for the three successive phases. The increased rate of PCr hydrolysis, and also the loss of fine force control evident in the force records are consistent with increased involvement of large, fast-fatiguable units later in the contraction. Copyright © 2002 John Wiley & Sons, Ltd. [source] Actin-dependent motility of melanosomes from fish retinal pigment epithelial (RPE) cells investigated using in vitro motility assaysCYTOSKELETON, Issue 2 2004E. L. McNeil Melanosomes (pigment granules) within retinal pigment epithelial (RPE) cells of fish and amphibians undergo massive migrations in response to light conditions to control light flux to the retina. Previous research has shown that melanosome motility within apical projections of dissociated fish RPE cells requires an intact actin cytoskeleton, but the mechanisms and motors involved in melanosome transport in RPE have not been identified. Two in vitro motility assays, the Nitella assay and the sliding filament assay, were used to characterize actin-dependent motor activity of RPE melanosomes. Melanosomes applied to dissected filets of the Characean alga, Nitella, moved along actin cables at a mean rate of 2 ,m/min, similar to the rate of melanosome motility in dissociated, cultured RPE cells. Path lengths of motile melanosomes ranged from 9 to 37 ,m. Melanosome motility in the sliding filament assay was much more variable, ranging from 0.4,33 ,m/min; 70% of velocities ranged from 1,15 ,m/min. Latex beads coated with skeletal muscle myosin II and added to Nitella filets moved in the same direction as RPE melanosomes, indicating that the motility is barbed-end directed. Immunoblotting using antibodies against myosin VIIa and rab27a revealed that both proteins are enriched on melanosome membranes, suggesting that they could play a role in melanosome transport within apical projections of fish RPE. Cell Motil. Cytoskeleton 58:71,82, 2004. © 2004 Wiley-Liss, Inc. [source] Amount and controls of the quaternary denudation in the Ardennes massif (western Europe)EARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2009A. Demoulin Abstract It is still debated whether the primary control on the middle Pleistocene denudation of the uplifted Ardennes massif (western Europe) is tectonic or climatic. Here, based on geomorphological observations, we calculate the amount of river incision and interfluve denudation in the Meuse basin upstream of Maastricht since 0·7 Ma and we show that the main response to tectonic forcing was incision. This allows us to provide first-order estimates of the tectonic and climatic contributions to the denudation of the Ardennes. From a dataset of 71 remnants of a terrace level dated ,0·7 Ma, we first derive a basin-scale functional relationship linking incision with distances to the regional base level (Lc) and to the source (Ls) in the Ourthe basin (pertaining to the Ardennian part of the Meuse basin). Expressed as I = I0*(1 , a*Lcb/Lsc), I0 being the incision measured at the basin outlet, this relationship calculates that river incision has removed 84 km3 of rock in the Meuse basin upstream of Maastricht since 0·7 Ma. In the same time, 292 km3 were eroded from the interfluves. A comparison of these volumes shows that the tectonically forced river incision accounts for ,22% of the total post-0·7 Ma denudation. Furthermore, the mean denudation rate corresponding to our geomorphological estimate of the overall denudation in the Meuse basin since 0·7 Ma amounts to 27 mm/ky, a figure significantly lower than the ,40 mm/ky mean rate derived from 10Be studies of terrace deposits of the Meuse (Schaller et al., 2004). This suggests that, taken as a basin average, the 10Be-derived rate is overestimated, probably due to an overrepresentation of the erosion products of the rapidly incising valleys in the alluvial deposits. Copyright © 2009 John Wiley & Sons, Ltd. [source] Sediment transport in a highly regulated fluvial system during two consecutive floods (lower Ebro River, NE Iberian Peninsula)EARTH SURFACE PROCESSES AND LANDFORMS, Issue 4 2005Damia Vericat Abstract The transfer of sediment through a highly regulated large fluvial system (lower Ebro River) was analysed during two consecutive floods by means of sediment sampling. Suspended sediment and bedload transport were measured upstream and downstream of large reservoirs. The dams substantially altered flood timing, particularly the peaks, which were advanced downstream from the dams for flood control purposes. The suspended sediment yield upstream from the dams was 1 700 000 tonnes, which represented nearly 99 per cent of the total solid yield. The mean concentrations were close to 0·5 g l,1. The sediment yield downstream from the dams was an order of magnitude lower (173 000 tonnes), showing a mean concentration of 0·05 g l,1. The dams captured up to 95 per cent of the fine sediment carried in suspension in the river channel, preventing it from reaching the lowermost reaches of the river and the delta plain. Total bedload transport upstream from the dams was estimated to be about 25 000 tonnes, only 1·5 per cent of the total load. The median bedload rate was 100 gms,1. Below the dams, the river carried 178 000 tonnes, around 51 per cent of the total load, at a mean rate of 250 g ms,1. The results of sediment transport upstream and downstream from the large dams illustrate the magnitude of the sediment deficit in the lower Ebro River. The river mobilized a total of 350 000 tonnes in the downstream reaches, which were not replaced by sediment from upstream. Therefore, sediment was necessarily entrained from the riverbed and channel banks, causing a mean incision of 33 mm over the 27 km long study reach, altogether a significant step towards the long-term degradation of the lower Ebro River. Copyright © 2005 John Wiley & Sons, Ltd. [source] Discrepancy between acute and chronic toxicity induced by imidacloprid and its metabolites in Apis melliferaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2001Séverine Suchail Abstract Imidaclopridi a systemic nitroguanidine insecticide that belongs to theneonicotinoid family. As an agonist of the acetylcholine receptor, it attacks the insect nervous system and is extremely effective against various sucking and mining pests. Oral acute and chronic toxicity of imidacloprid and its main metabolites (5-hydroxyimidacloprid, 4,5-dihydroxyimidacloprid, desnitroimidacloprid, 6-chloronicotinic acid, olefin, and urea derivative) were investigated in Apis mellifera. Acute intoxication by imidacloprid or its metabolites resulted in the rapid appearance of neurotoxicity symptoms, such as hyperresponsiveness, hyperactivity, and trembling and led to hyporesponsiveness and hypoactivity. For acute toxicity tests, bees were treated with doses of toxic compounds ranging from 1 to 1,000 ng/bee (10,10,000 ,g/kg). Acute toxicity (LD50) values of imidacloprid were about 60 ng/bee (600 ,g/kg) at 48 h and about 40 ng/bee (400 ,g/kg) at 72 and 96 h. Out of the six imidacloprid metabolites tested, only two (5-hydroxyimidacloprid and olefin) exhibited a toxicity close to that of imidacloprid. Olefin LD50 values were lower than those of imidacloprid. The 5-hydroxyimidacloprid showed a lower toxicity than imidacloprid with a LD50 four to six times higher than that of imidacloprid. Urea also appeared as a compound of nonnegligible toxicity by eliciting close to 40% mortality at 1,000 ng/bee (10,000 ,g/kg). However, no significant toxicity was observed with 4,5-dihydroxyimidacloprid, 6-chloronicotinic acid, and desnitroimidacloprid in the range of doses tested. To test chronic toxicity, worker bees were fed sucrose solutions containing 0.1, 1, and 10 ,g/L of imidacloprid and its metabolites for 10 d. Fifty percent mortality was reached at approximately 8 d. Hence, considering that sucrose syrup was consumed at the mean rate of 12 ,l/d and per bee, after an 8-d period the cumulated doses were approximately 0.01, 0.1, and 1 ng/bee (0.1, 1, and 10 ,g/kg). Thus, all tested compounds were toxic at doses 30 to 3,000 (olefin), 60 to 6,000 (imidacloprid), 200 to 20,000 (5-OH-imidacloprid), and >1,000 to 100,000 (remaining metabolites) times lower than those required to produce the same effect in acute intoxication studies. For all products tested, bee mortality was induced only 72 h after the onset of intoxication. [source] Respiration and thermogenesis by cones of the Australian cycad Macrozamia machiniiFUNCTIONAL ECOLOGY, Issue 6 2004R. S. SEYMOUR Summary 1While cycads are often considered to be wind-pollinated, it is now clear that insects are pollen vectors in many species. This study addresses the role of thermogenesis in pollination biology of the dioecious cycad Macrozamia machinii P.I. Forster & D.L. Jones. 2The patterns of thermogenesis in intact male and female cones were assessed with thermometry and respirometry throughout the pollination period in the field. 3Thermogenic episodes in male cones occurred from about 17.00,00.00 h on successive evenings, in association with dehiscence of sporangia and presence of their pollinating weevils (Tranes sp.). 4Temperatures of the 167 g male cones rose ,6 °C above ambient, and mean rate of oxygen consumption peaked at 7·7 µmol s,1 (3·6 W). Regulation of male cone temperature was not evident, and thermogenesis of female cones was insignificant. 5Male cones probably heat to augment scent production and enhance weevil activity, including mating and egg-laying, but female cones may benefit from reduced visitation and freedom from damage by weevil larvae. Male cones may be sacrificial in providing the reward to the pollinators while the female cones are safeguarded. [source] Measuring metabolic rate in the field: the pros and cons of the doubly labelled water and heart rate methodsFUNCTIONAL ECOLOGY, Issue 2 2004P. J. Butler Summary 1Measuring the metabolic rate of animals in the field (FMR) is central to the work of ecologists in many disciplines. In this article we discuss the pros and cons of the two most commonly used methods for measuring FMR. 2Both methods are constantly under development, but at the present time can only accurately be used to estimate the mean rate of energy expenditure of groups of animals. The doubly labelled water method (DLW) uses stable isotopes of hydrogen and oxygen to trace the flow of water and carbon dioxide through the body over time. From these data, it is possible to derive a single estimate of the rate of oxygen consumption () for the duration of the experiment. The duration of the experiment will depend on the rate of flow of isotopes of oxygen and hydrogen through the body, which in turn depends on the animal's size, ranging from 24 h for small vertebrates to up to 28 days in Humans. 3This technique has been used widely, partly as a result of its relative simplicity and potential low cost, though there is some uncertainty over the determination of the standard error of the estimate of mean . 4The heart rate (fH) method depends on the physiological relationship between heart rate and . 5If these two quantities are calibrated against each other under controlled conditions, fH can then be measured in free-ranging animals and used to estimate . 6The latest generation of small implantable data loggers means that it is possible to measure fH for over a year on a very fine temporal scale, though the current size of the data loggers limits the size of experimental animals to around 1 kg. However, externally mounted radio-transmitters are now sufficiently small to be used with animals of less than 40 g body mass. This technique is gaining in popularity owing to its high accuracy and versatility, though the logistic constraint of performing calibrations can make its use a relatively extended process. [source] Tropical forest tree mortality, recruitment and turnover rates: calculation, interpretation and comparison when census intervals varyJOURNAL OF ECOLOGY, Issue 6 2004SIMON L. LEWIS Summary 1Mathematical proofs show that rate estimates, for example of mortality and recruitment, will decrease with increasing census interval when obtained from censuses of non-homogeneous populations. This census interval effect could be confounding or perhaps even driving conclusions from comparative studies involving such rate estimates. 2We quantify this artefact for tropical forest trees, develop correction methods and re-assess some previously published conclusions about forest dynamics. 3Mortality rates of > 50 species at each of seven sites in Africa, Latin America, Asia and Australia were used as subpopulations to simulate stand-level mortality rates in a heterogeneous population when census intervals varied: all sites showed decreasing stand mortality rates with increasing census interval length. 4Stand-level mortality rates from 14 multicensus long-term forest plots from Africa, Latin America, Asia and Australia also showed that, on average, mortality rates decreased with increasing census interval length. 5Mortality, recruitment or turnover rates with differing census interval lengths can be compared using the mean rate of decline from the 14 long-term plots to standardize estimates to a common census length using ,corr = , × t0.08, where , is the rate and t is time between censuses in years. This simple general correction should reduce the bias associated with census interval variation, where it is unavoidable. 6Re-analysis of published results shows that the pan-tropical increase in stem turnover rates over the late 20th century cannot be attributed to combining data with differing census intervals. In addition, after correction, Old World tropical forests do not have significantly lower turnover rates than New World sites, as previously reported. Our pan-tropical best estimate adjusted stem turnover rate is 1.81 ± 0.16% a,1 (mean ± 95% CI, n = 65). 7As differing census intervals affect comparisons of mortality, recruitment and turnover rates, and can lead to erroneous conclusions, standardized field methods, the calculation of local correction factors at sites where adequate data are available, or the use of our general standardizing formula to take account of sample intervals, are to be recommended. [source] Improving glycemic control in medical inpatients: A pilot studyJOURNAL OF HOSPITAL MEDICINE, Issue 1 2008BCPS, Jennifer M. Trujillo PharmD Abstract BACKGROUND Inpatient hyperglycemia is associated with poor patient outcomes. Current guidelines recommend that in an inpatient non-ICU setting there be treatment to achieve a glucose level below 180 mg/dL. METHODS Objectives of this prospective quality-improvement pilot study were to implement a subcutaneous insulin protocol on a general medicine service, to identify barriers to implementation, and to determine the effect of this protocol on glycemic control. Eighty-nine patients with a preexisting diagnosis of type 2 diabetes or inpatient hyperglycemia were eligible. Study outcomes included resident acceptance of the protocol, insulin-ordering practices, and mean rate of hyperglycemia (glucose > 180 mg/dL) per person. Results were compared with those of a previously conducted observational study. RESULTS Residents agreed to use the protocol in 56% of cases. Reasons for declining the protocol included severity of a patient's other disease states, desire to titrate oral medications, and fear of hypoglycemia. Basal and nutritional insulin were prescribed more often in the pilot group compared with at baseline (64% vs. 49% for basal, P = .05; 13% vs. 0% for nutritional, P < .001). Basal insulin was started after the first full hospital day in 42% of patients, and only one-third of patients with any hypo- or hyperglycemia had any subsequent changes in their insulin orders. The mean rate of hyperglycemia was not significantly different between groups (31.6% of measurements per patient vs. 33.3%, P = .85). CONCLUSIONS Adherence to a new inpatient subcutaneous insulin protocol was fair. Barriers included fear of hypoglycemia, delays in starting basal insulin, and clinical inertia. Quality improvement efforts likely need to target these barriers to successfully improve inpatient glycemic control. Journal of Hospital Medicine 2008;3:55,63. © 2008 Society of Hospital Medicine. [source] METABOLIC AND ECOLOGICAL CONSTRAINTS IMPOSED BY SIMILAR RATES OF AMMONIUM AND NITRATE UPTAKE PER UNIT SURFACE AREA AT LOW SUBSTRATE CONCENTRATIONS IN MARINE PHYTOPLANKTON AND MACROALGAE,JOURNAL OF PHYCOLOGY, Issue 2 2007T. Alwyn Marine phytoplankton and macroalgae acquire important resources, such as inorganic nitrogen, from the surrounding seawater by uptake across their entire surface area. Rates of ammonium and nitrate uptake per unit surface area were remarkably similar for both marine phytoplankton and macroalgae at low external concentrations. At an external concentration of 1 ,M, the mean rate of nitrogen uptake was 10±2 nmol·cm,2·h,1 (n=36). There was a strong negative relationship between log surface area:volume (SA:V) quotient and log nitrogen content per cm2 of surface (slope=,0.77), but a positive relationship between log SA:V and log maximum specific growth rate (,max; slope=0.46). There was a strong negative relationship between log SA:V and log measured rate of ammonium assimilation per cm2 of surface, but the slope (,0.49) was steeper than that required to sustain ,max (,0.31). Calculated rates of ammonium assimilation required to sustain growth rates measured in natural populations were similar for both marine phytoplankton and macroalgae with an overall mean of 6.2±1.4 nmol·cm,2·h,1 (n=15). These values were similar to maximum rates of ammonium assimilation in phytoplankton with high SA:V, but the values for algae with low SA:V were substantially less than the maximum rate of ammonium assimilation. This suggests that the growth rates of both marine phytoplankton and macroalgae in nature are often constrained by rates of uptake and assimilation of nutrients per cm2 surface area. [source] Molecular phylogenetic analysis of Leibnitzia Cass. (Asteraceae: Mutisieae: Gerbera -complex), an Asian,North American disjunct genusJOURNAL OF SYSTEMATICS EVOLUTION, Issue 3 2010Kristen E. BAIRD Abstract Leibnitzia comprises six species of perennial herbs that are adapted to high elevation conditions and is one of only two Asteraceae genera known to have an exclusively disjunct distribution spanning central to eastern Asia and North America. Molecular phylogenetic analysis of Leibnitzia and other Gerbera -complex members indicates that Leibnitzia is monophyletic, which is in contrast with our expectation that the American Leibnitzia species L. lyrata and L. occimadrensis would be more closely related to another American member of the Gerbera -complex, namely Chaptalia. Ancestral area reconstructions show that the historical biogeography of the Gerbera -complex mirrors that of the entire Asteraceae, with early diverging lineages located in South America that were followed by transfers to Africa and Eurasia and, most recently, to North America. Intercontinental transfer of Leibnitzia appears to have been directed from Asia to North America. Independent calibrations of nuclear (ribosomal DNA internal transcribed spacer region) and chloroplast (trnL,rpl32 intron) DNA sequence data using relaxed clock methods and either mean rate or fossil-based priors unanimously support Miocene and younger divergence times for Gerbera -complex taxa. The ages are not consistent with most Gondwanan vicariance episodes and, thus, the global distribution of Gerbera -complex members must be explained in large part by long-distance dispersal. American species of Leibnitzia are estimated to have diverged from their Asian ancestor during the Quaternary (ca. 2 mya) and either migrated overland to North America via Beringia and retreated southwards along high elevation corridors to their present location in southwestern North America or were dispersed long distance. [source] FIELD EXPERIMENTS SHOW THAT ACOUSTIC PINGERS REDUCE MARINE MAMMAL BYCATCH IN THE CALIFORNIA DRIFT GILL NET FISHERYMARINE MAMMAL SCIENCE, Issue 2 2003Jay Barlow Abstract A controlled experiment was carried out in 1996,1997 to determine whether acoustic deterrent devices (pingers) reduce marine mammal bycatch in the California drift gill net fishery for swordfish and sharks. Using Fisher's exact test, bycatch rates with pingers were significantly less for all cetacean species combined (P < 0.001) and for all pinniped species combined (P= 0.003). For species tested separately with this test, bycatch reduction was statistically significant for short-beaked common dolphins (P= 0.001) and California sea lions (P= 0.02). Bycatch reduction is not statistically significant for the other species tested separately, but sample sizes and statistical power were low, and bycatch rates were lower in pingered nets for six of the eight other cetacean and pinniped species. A log-linear model relating the mean rate of entanglement to the number of pingers deployed was fit to the data for three groups: short-beaked common dolphins, other cetaceans, and pinnipeds. For a net with 40 pingers, the models predict approximately a 12-fold decrease in entanglement for short-beaked common dolphins, a 4-fold decrease for other cetaceans, and a 3-fold decrease for pinnipeds. No other variables were found that could explain this effect. The pinger experiment ended when regulations were enacted to make pingers mandatory in this fishery. [source] Latest news and product developmentsPRESCRIBER, Issue 9 2008Article first published online: 21 MAY 200 Dabigatran launched Dabigatran (Pradaxa), an orally active direct thrombin inhibitor, has been introduced for the prophylaxis of venous thromboembolism in patients undergoing elective total hip or knee replacement. Treatment is initiated within four hours of surgery and continued for 10 days after knee replacement and 28-35 days after hip replacement. Dabigatran has been shown to be as effective and well tolerated as enoxaparin (Clexane). The launch was widely publicised in the lay media; the charity Lifeblood claimed it could help prevent tens of thousands of deaths. NICE is preparing a technology appraisal of the new agent but it has not announced a publication date. Loop diuretics may increase bone loss Continuous use of a loop diuretic appears to double the rate of bone loss in men compared with nonusers, an observational study suggests (Ann Intern Med 2008;168: 735-40). Up to five years' follow-up of 3269 men aged over 65 revealed that the mean rate of bone loss in the hip among those who did not use a loop diuretic was 0.33 per cent compared with 0.78 per cent among users and 0.58 per cent in those who had intermittently used a loop diuretic. Use of these agents should be included as a risk factor for fractures, the authors suggest. Rosuvastatin not for heart failure patients? Prescribers should pause before using rosuvastatin (Crestor). in patients with heart failure and ischaemic heart disease, the National Prescribing Centre (NPC). says. Commenting on the CORONA trial (N Engl J Med 2008; published online 5 Nov 2007; 10.1056/NEJMoa 0706201)., which found no reduction in cardiovascular events or mortality in older patients with systolic heart failure despite a reduction in LDL-C, the NPC says GPs should still consider evidence-based statins such as simvastatin in this patient group. The reason for the outcome of CORONA is unclear but the NPC points out that not all statins affect mortality equally. Rimonabant CV benefits sustained Two-year follow-up of the RIO-Europe trial has shown that the benefits of rimonabant (Acomplia). on weight loss and cardiovascular risk factors are sustained with continuing treatment (Eur Heart J 2008; published online doi: 10.1093/ eurheartj/ehn076). In addition to a dietary deficit of 600kcal per day, rimonabant 20mg per day achieved greater mean weight loss (5.5 vs 1.2kg). and improvements in waist circumference, HDL-cholesterol, triglycerides, fasting glucose and insulin levels, insulin resistance, and metabolic syndrome prevalence compared with placebo. Many patients discontinued treatment (placebo 42 per cent, rimonabant 45 per cent). but, although psychiatric events were more common with rimonabant during the first year, there was little difference in patients remaining in the second year. Early glatiramer cuts MS progression risk Early treatment with glatiramer acetate (Copaxone). appears to reduce the risk of progression to multiple sclerosis (MS), according to a study presented at the 60th Annual Meeting of the American Academy of Neurology in Chicago. Interim analysis of the PreCISE trial showed that, in patients with a single episode and MRI suggestive of MS, glatiramer was associated with a lower incidence of progression to a second episode of MS compared with placebo (25 vs 43 per cent). The placebo arm of the trial has now been stopped. NRT before quitting Beginning nicotine replacement therapy (NRT) before stopping smoking may double the six-month success rate compared with beginning treatment on the scheduled quit day, a meta-analysis suggests (Addiction 2008;103: 557-63). The analysis of four trials involving 755 participants found that starting NRT two to four weeks before the agreed quit date was twice as likely as the conventional strategy to achieve abstinence after six weeks and six months. Copyright © 2008 Wiley Interface Ltd [source] Latest news and product developmentsPRESCRIBER, Issue 6 2007Article first published online: 8 JUN 200 Initial macrolide better for pneumonia? An observational study has suggested that initial treatment with a macrolide antibiotic (such as erythromycin) may be more effective than a fluoroquinolone (like ciprofloxacin) or tetracycline as initial treatment for community acquired pneumonia and bacteraemia (Chest 2007;131:466-73). The US review of 2209 hospital episodes found that macrolide therapy was associated with a 40 per cent lower risk of death during hospital stay or within 30 days and of hospital readmission within 30 days of discharge. By contrast, no such benefit was apparent with fluoroquinolones or tetracycline. Two-year safety data for inhaled insulin Compared with sc insulin, inhaled insulin (Exubera) is associated with a small early decrease in lung function in the first three months of therapy but no further difference for up to two years (Diabetes Care 2007;30: 579-85). The comparative trial found that FEV1 declined at a mean rate of 0.051 litres per year with inhaled insulin and 0.034 litres per year with sc insulin, but there was no significant difference in the rates of decline after three months. Inhaled insulin was associated with a higher incidence of cough (37.6 vs 13.1 per cent) but a lower incidence of severe hypoglycaemic events (2.8 vs 4.1 events per 100 subject- months) and mean weight gain was 1.25kg less. Fracture risk warning with rosiglitazone GlaxoSmithKline has warned US prescribers that rosiglitazone may be associated with an increased risk of fractures. The company says information for prescribers in Europe will follow shortly. The warning comes from the ADOPT study (N Engl J Med 2006;355:2427-43), which found a significantly higher incidence of fractures of the humerus, hand and foot among women taking rosiglitazone (9.3 per cent) than with metformin (5.1 per cent) or glibenclamide (3.5 per cent). There was no difference in fracture incidence among men. The company recommends that fracture risk should be considered for women taking or about to take rosiglitazone. Oral treatment for grass pollen allergy A new treatment for allergic rhinitis due to grass pollen allergy has been introduced by ALK-Abelló. Grazax is a sublingual tablet containing a stan-dardised dose of allergen from the pollen of timothy grass. Treatment should be initiated by a specialist four months before the onset of the allergy season and continued throughout the season. Adverse effects include oral and ear pruritus, nasopharyngitis and mouth oedema. A month's treatment at the recommended dose of one tablet daily costs £67.50. Frequent analgesics linked with hypertension Men who take analgesics regularly have an increased frequency of hypertension, a US study has shown (Arch Intern Med 2007;167:394-9). The US Health Professionals Follow-Up study evaluated the use of NSAIDs, paracetamol and aspirin in 16 031 men with normal blood pressure and followed them up for four years. Compared with those who did not report analgesic use, the risk of hypertension was increased by 38 per cent for NSAID use, 34 per cent for paracetamol and 26 per cent for aspirin, all for for six or seven days a week. Similar risks were found when anal- gesic use was determined according to the number of tablets taken. The authors acknowledge the increased risk is modest, but point out that the implications may nonetheless be important because analgesics are widely used. Multiples do most pharmacist MURs Uptake of medicines use reviews (MURs) by pharmacists was modest in 2005 and most reviews were carried out by pharmacy chains rather than independent contractors, a new study has shown (Pharm J 2007;278:218-23). The survey of PCTs and SHAs in England and Wales found that, although 38 per cent of community pharmacies claimed payments for the service, 84 per cent of MURs were carried out by pharmacy chains. Uptake was low, amounting to only 7 per cent of the maximum possible number of MURs. Patients see information needs differently There is a mismatch in the perceptions of patients and health professionals about the purpose of written information about medicines, a systematic review has concluded (Health Technol Assess 2007;11:1-178). Some health professionals believe the main purpose of information is to promote compliance, whereas patients want information to help them make decisions about their treatment, including not taking it. In particular, patients want information on adverse effects, but health professionals have reservations about providing it. Aspirin for all women over 65? All women over 65 should take low-dose aspirin if the benefits are likely to outweigh the risk of adverse effects, according to new guidelines from the American Heart Association on preventing cardiovascular disease in women (published online 19 Feb 2007;doi: 10.1161/circulationaha.107.181546). The guidelines have moved away from the long-established Framingham model of risk assessment to categorising three levels of risk: high (heart disease or other relevant disease present), at risk (at least one risk factor) and optimal (healthy lifestyle, no risk factors). Low-dose aspirin is recommended for all women at high risk, for women aged 65 or over when reducing the risk of MI or ischaemic stroke outweighs the risk of adverse effects, and for younger women when reducing the risk of ischaemic stroke outweighs that of toxicity. Combination inhaler therapy Combining an inhaled long-acting bronchodilator with a steroid reduces COPD exacerbations but not all-cause mortality, a three-year trial has shown (N Engl J Med 2007;356:775-89). However, inhaled steroids appear to increase the risk of pneumonia. The TORCH trial randomised 6112 patients (FEV1<60 per cent predicted) to treatment with salmeterol 50µg plus fluticasone 500µg (Seretide) twice daily, salmeterol (Serevent) or fluticasone (Flixotide) as monotherapy, or placebo. All-cause mortality rates were 12.6, 13.5, 16.0 and 15.2 per cent respectively; the risk of death was 17 per cent lower with combined therapy, but the difference did not reach statistical significance. The combination reduced the incidence of exacerbations by 25 per cent and improved health status and FEV1. Use of fluticasone was not associated with more ocular or bone disorders, but there was an increased incidence of pneumonia among users (19.6 per cent with combined therapy and 18.3 per cent with fluticasone vs 12.3 per cent with placebo). Seretide is currently licensed in the UK for use in patients with FEV1 <50 per cent predicted. Tamoxifen long- term benefits Women with breast cancer who take tamoxifen for five to eight years continue to have a lower risk of recurrence for 10-20 years, long-term follow-up of two blinded trials has shown (J Nat Cancer Inst 2007; 99:258-60, 272-90). The frequency of adverse effects was markedly reduced when treatment ended, changing the balance of risk and benefit. Copyright © 2007 Wiley Interface Ltd [source] Broken ribs: Paleopathological analysis of costal fractures in the human identified skeletal collection from the Museu Bocage, Lisbon, Portugal (late 19th to middle 20th centuries)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Vítor Matos Abstract Although rarely reported in the anthropological literature, rib fractures are commonly found during the analysis of human skeletal remains of past and modern populations. This lack of published data precludes comparison between studies and restricts an accurate understanding either of the mechanisms involved in thoracic injuries or their impact on past societies. The present study aimed: 1) to report rib fracture prevalence in 197 individuals, 109 males, and 88 females, with ages at death ranging from 13 to 88 years old, from the Human Identified Skeletal Collection, Museu Bocage, Portugal (late 19th-middle 20th centuries); 2) to test the hypothesis that a higher prevalence of rib stress fractures existed in the 133 individuals who died from respiratory diseases, in a period before antibiotics. The macroscopic analysis revealed 23.9% (n = 47) of individuals with broken ribs. 2.6% (n = 124) out of 4,726 ribs observed were affected. Males presented more rib fractures, and a significantly higher prevalence was noted for older individuals. Fractures were more frequently unilateral (n = 34), left sided (n = 19) and mainly located on the shaft of ribs from the middle thoracic wall. Nineteen individuals presented adjacent fractured ribs. Individuals who died from pulmonary diseases were not preferentially affected. However, a higher mean rate of fractures was found in those who died from pneumonia, a scenario still common nowadays. Since rib involvement in chest wall injury and its related outcomes are important issues both for paleopathology and forensic anthropology, further investigations are warranted. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] The effect of alcohol on radiographic progression in rheumatoid arthritisARTHRITIS & RHEUMATISM, Issue 5 2010M. J. Nissen Objective Alcohol consumption reduces the risk of development of rheumatoid arthritis (RA) and significantly attenuates the development of erosive arthritis in animal models. It remains unknown whether alcohol consumption influences joint damage progression in RA. This study was undertaken to compare the rates of radiographic damage progression in alcohol drinkers and nondrinkers in a large prospective cohort of patients with RA. Methods All patients in the population-based Swiss Clinical Quality Management in RA registry database with at least 2 sequential radiographs were included. Joint erosions were assessed in 38 joints in the hands and feet using a validated scoring method. The rate of progression of erosions was analyzed using multivariate regression models for longitudinal data and was adjusted for potential confounders. Results The study included 2,908 patients with RA with a mean of 4 sequential radiographs and 3.9 years of followup. A trend toward reduced radiographic progression existed in drinkers compared with nondrinkers, with a mean rate of erosive progression of 0.99% (95% confidence interval [95% CI] 0.89,1.09) and 1.13% (95% CI 1.01,1.26) at 1 year, respectively. Alcohol consumption displayed a J-shaped dose-response effect, with a more favorable evolution in occasional consumers (P = 0.01) and daily consumers (P = 0.001) as compared with nondrinkers, while heavy drinkers demonstrated worse radiographic evolution (P = 0.0001). We found significant effect modification by sex, with male drinkers displaying significantly less erosive progression compared with male nondrinkers (mean 0.86% [95% CI 0.70,1.03] versus 1.35% [95% CI 1.02,1.67]; P = 0.007). Conclusion Our findings indicate a trend toward reduced radiographic progression in alcohol drinkers compared with nondrinkers, specifically in occasional and daily alcohol consumers. In particular, male patients with RA who consume alcohol demonstrate less radiographic progression than do male nondrinkers. [source] Original Article: Rate of X chromosome aneuploidy in young fertile women: Comparison of cultured and uncultured cell preparations using fluorescence in situ hybridisationAUSTRALIAN AND NEW ZEALAND JOURNAL OF OBSTETRICS AND GYNAECOLOGY, Issue 4 2010Kirralee PATTON Background:, X chromosome aneuploidy <10% in female patients is a routinely used reporting limit in diagnostic cytogenetics. X aneuploidy (<10%) is commonly detected in women investigated for infertility or recurrent miscarriages. It is unclear if this aneuploidy is causally relevant or related to the culture process. Information about the background rate of X aneuploidy in young fertile women would be helpful in resolving this issue. Aim:, This study aimed to investigate the rate of X aneuploidy in young fertile women in cultured and uncultured samples to determine if the commonly used <10% limit is relevant. Method:, Volunteers (aged 22,40 years) with proven fertility (n = 78) participated. The number of X chromosome signals in 500 cultured and 500 uncultured preparations were enumerated using FISH. Results:, Significantly, all participants had <5% X aneuploidy in both preparations, X chromosome loss occurred (2.4%) more frequently than gain (0.7%). Cultured preparations had a mean of 2.1% cells with X chromosome aneuploidy (95% CI 1.9,2.3%) compared with a mean rate of 0.9% aneuploidy in uncultured preparations (95% CI 0.7,1.1%). The relative risk for cultured preparations having X aneuploidy compared with uncultured cells was 2.33 (P < 0.001) (95% CI 2.1,2.6). Conclusion:, Young fertile women had <5% X aneuploidy. The rate of X aneuploidy was higher in cultured (2.1%) compared with uncultured (0.9%) preparations (P < 0.001). This data may provide useful background information when considering low level X aneuploidy in other groups of women with clinical indications for karyotype. [source] Unanticipated Effects of Stand Dynamism on Amazonian Tree DiversityBIOTROPICA, Issue 4 2010Susan G. W. Laurance ABSTRACT We assessed a general hypothesis of tropical tree diversity that predicts that species richness will be positively correlated with stand dynamism. Our analysis was based one of the largest and longest-running datasets on Amazonian trees (,10 cm diameter at breast height), with data collected over a 23-yr period within 66 1 ha plots spanning a large (1000 km2) landscape. Within these plots, maximum tree-species richness (329 species/ha) and Fisher's , values (227.5) were among the highest ever recorded. Contrary to the diversity-dynamism concept, tree species richness in our landscape was significantly and negatively associated with stand dynamism (measured as the mean rate of annual tree turnover). Because of this unexpected finding, we critically re-evaluated the relationship between stand dynamism and tree diversity across the Amazon basin and the tropics as a whole. With the inclusion of additional data we found that the relationship between stand dynamism and tree diversity becomes non-significant at larger spatial scales. Abstract in Portuguese is available at http://www.blackwell-synergy.com/loi/btp [source] Cluster randomised trial of an active, multifaceted educational intervention based on the WHO Reproductive Health Library to improve obstetric practicesBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 1 2007AM Gülmezoglu Objective, We conducted a trial to evaluate the effect of an active, multifaceted educational strategy to promote the use of the WHO Reproductive Health Library (RHL) on obstetric practices. Design, Cluster randomised trial. The trial was assigned the International Standardised Randomised Controlled Trial Number ISRCTN14055385. Settings, Twenty-two hospitals in Mexico City and 18 in the Northeast region of Thailand. Methods, The intervention consisted primarily of three interactive workshops using RHL over a period of 6 months. The focus of the workshops was to provide access to knowledge and enable its use. A computer and support for using both the computer and RHL were provided at each hospital. The control hospitals did not receive any intervention. Main outcome measures, The main outcome measures were changes in ten selected clinical practices as recommended in RHL starting approximately four to six months after the third workshop. Clinical practice data were collected at each hospital from 1000 consecutively delivered women or for a 6-month period whichever was reached sooner. Results, The active, multifaceted educational intervention we employed did not affect the ten targeted practices in a consistent and substantive way. Iron/folate supplementation, uterotonic use after birth and breastfeeding on demand were already frequently practiced, and we were unable to measure external cephalic version. Of the remaining six practices, selective, as opposed to routine episiotomy policy increased in the intervention group (difference in adjusted mean rate = 5.3%; 95% CI ,0.1 to 10.7%) in Thailand, and there was a trend towards an increased use of antibiotics at caesarean section in Mexico (difference in adjusted mean rate = 19.0%; 95% CI: ,8.0 to 46.0%). There were no differences in the use of labour companionship, magnesium sulphate use for eclampsia, corticosteroids for women delivering before 34 weeks and vacuum extraction. RHL awareness (24.8,65.5% in Mexico and 33.9,83.3% in Thailand) and use (4.8,34.9% in Mexico and 15.5,76.4% in Thailand) increased substantially after the intervention in both countries. Conclusion, The multifaceted, active strategy to provide health workers with the knowledge and skills to use RHL to improve their practice led to increased access to and use of RHL, however, no consistent or substantive changes in clinical practices were detected within 4,6 months after the third workshop. [source] Monitoring individual compliance in glaucoma patients used to topical therapyACTA OPHTHALMOLOGICA, Issue 2007AM BRON Purpose: Individual compliance with Brimonidine eye drops was studied in glaucoma patients and ocular hypertensives. Methods: Conventional Brimonidine vials were equipped with a microprocessor-controlled monitoring device capable to record date and time of each eye drop application including ambient temperature. After written informed consent, glaucoma and ocular hypertensive patients used to eye drop therapy were randomly assigned to Brimonidine therapy b.i.d or t.i.d daily for 4 weeks. Results: Twenty six males and fourteen females aged 69 ± 11 years [42-89] were enrolled in this study. According to the monitoring devices all patients were non-compliant with regard to total dose and coverage. Electronic records revealed a mean of 1.5 (range: 1.1-2.0) applications per day for patients assigned to Brimonidine 2x daily with a mean treatment interval of 16.8 hours (range: 12.1-22.2 h). Patients on Brimonidine 3x daily showed a mean rate of 1.9 (range: 1.8-2.7) applications per day and a mean treatment interval of 11.9 h (range: 9.1-13.9 h). One patient discontinued therapy after day 7 (12 applications) and one after day 1 (1 application only). No difference was observed between IOP at baseline and after one month (p=0.16). Conclusions: The monitoring devices permit to detect individual non-compliance with regard to missed doses, non-treatment intervals. Our data confirm the need for larger studies on individual compliance with topical ocular therapy in glaucoma. [source] Paediatric pseudophakia: analysis of intraocular lens power and myopic shiftCLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 3 2007William F Astle MD Abstract Background: At the Alberta Children's Hospital, the authors have been performing paediatric cataract extraction with intraocular lens (IOL) implant for over 10 years. The authors examined the amount of myopic shift that occurs in various age groups and cataract types, in order to evaluate the success of predicting the appropriate power of IOL to implant. Methods: This study is a retrospective review children undergoing small incision posterior chamber foldable IOL implantation between age 1 month and 18 years, from 1995 to 2005. 163 eyes of 126 patients underwent surgery. All patients were followed for a minimum of 6 months postoperatively. The children were divided into four groups at time of surgery: Group A: 1,24 months, Group B: 25,48 months, Group C: 49,84 months, Group D: 85 months,18 years. Results: The mean target refraction for the groups were: Group A: +6.37 D, Group B: +4.66 D, Group C: +1.95 D, and Group D: +0.97 D. Children under 4 years experienced the most myopic shift and the largest mean rate of refractive change per year. Mean change Group A: ,5.43 D, Group B: ,4.16 D, Group C: ,1.58 D, Group D: ,0.71 D. Eighty-nine per cent of patients with unilateral cataracts had a postoperative refraction within 3.00 D of the fellow eye at last follow-up visit (mean = 3.16 years). Conclusions: The rate of myopic shift is high in children under age 4 years at time of surgery, shifting as much as ,12.00 D. The mean postoperative target refraction should probably be increased from previous literature recommendations. The patient's age at time of cataract surgery and the refractive power of fellow eye are all factors to consider when deciding what power IOL to surgically implant in a paediatric patient. [source] Self-motion and the origin of differential spatial scaling along the septo-temporal axis of the hippocampusHIPPOCAMPUS, Issue 7 2005Andrew P. Maurer Abstract Spatial scaling of place specific activity in the hippocampus varies systematically from the septal pole (high resolution) to the temporal pole (low resolution). Place fields get progressively larger, and the probability of observing a field in a given environment gets progressively smaller. It was previously found that decoupling movement in space from ambulation, by having the animal actively ride on a mobile platform, results in marked enlargement of the spatial scale factor in the dorsal hippocampus and a reduction in the increase in theta rhythm power with running speed, suggesting that a self-motion signal determines the spatial scale at which the hippocampal population vector updates. These results led to the hypothesis that the gain of the self-motion signal may vary systematically along the septo-temporal axis of the hippocampus. To test this hypothesis, EEG theta rhythm and ensembles of CA1 pyramidal cells and interneurons were recorded from the extreme dorsal and middle portions of the hippocampus. Pyramidal cell population vectors representing successive locations became decorrelated over substantially shorter distances in the dorsal than in the middle hippocampus. Dorsal pyramidal cells had smaller place fields, higher mean and peak firing rates, and higher intrinsic oscillation frequencies during track running than that of middle pyramidal cells. Both dorsal pyramidal cells and interneurons had more elevated mean rates during running, compared with rest, than that of the corresponding cell classes in the middle hippocampus, and both cell classes increased their rates more as a function of speed in the dorsal hippocampus. The amplitude, but not the frequency of fissure recorded theta rhythm, increased more as a function of running speed in the dorsal than in the middle hippocampus. We conclude that variation in the neuronal response to movement speed is the likely basis for the systematic variation in spatial scaling along the septo-temporal axis of the hippocampus. © 2005 Wiley-Liss, Inc. [source] A note on estimating urban roof runoff with a forest evaporation modelHYDROLOGICAL PROCESSES, Issue 8 2008J. H. C. Gash Abstract A model developed for estimating the evaporation of rainfall intercepted by forest canopies is applied to estimate measurements of the average runoff from the roofs of six houses made in a previous study of hydrological processes in an urban environment. The model is applied using values of the mean rates of wet canopy evaporation and rainfall derived previously for forests and an estimate of the roof storage capacity derived from the data collected in the previous study. Although the model prediction is sensitive to the value of storage capacity, close correlation between the modelled and measured runoff indicates that the model captures the essential processes. It is concluded that the process of evaporation from an urban roof is sufficiently similar to that from a forest canopy for forest evaporation models to be used to give a useful estimate of urban roof runoff. Copyright © 2007 John Wiley & Sons, Ltd. [source] DISTRIBUTION OF SEDIMENT PHOSPHORUS POOLS AND FLUXES IN RELATION TO ALUM TREATMENT,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 3 2000William F James ABSTRACT: The distribution of sediment physical characteristics, sediment phosphorus (P) pools, and laboratory-based rates of P release from the sediments were used to identify regions and dosage for alum treatment in Wind Lake, Wisconsin. Using variations in sediment moisture content, we identified an erosional zone at depths < 1.4 m and an accumulation zone at depths > 2.6 m. Mean concentrations of porewater P, loosely-bound P, iron- and aluminum-bound P, and mean rates of P release from sediments under anoxic conditions were high in the accumulation zone compared to sediment P characteristics in the erosional zone, indicating focusing of readily mobilized sediment P pools from shallow regions and accumulation to deep regions. We determined that a future alum treatment for control of internal P loading would be most effective at depths > 2.6 in the accumulation zone. The mean rate of anoxic P release from sediments encountered in the accumulation zone (8.3 mg m -2 d -1) was used in conjunction with a summer anoxic period of 122 d, and a treatment area of 1.6 km2 to estimate an internal P load of 1,600 kg to be controlled. Our results suggest that an understanding of the distribution of sediment P pools and P fluxes in lakes provides a strategy for estimating alum dosage and application areas. [source] Short-Term Changes in Heat Tolerance in the Alpine Cushion Plant Silene acaulis ssp. excapa [All.] J. Braun at Different AltitudesPLANT BIOLOGY, Issue 6 2000G. Neuner Abstract: The habit of cushion growth positively affects plant temperature but at the same may increase the risk of occasional overheating. In order to determine the adaptive response to short-term heat stress, we exposed S. acaulis cushions at field sites to controlled heat treatments using infrared lamps. Natural diurnal changes in heat tolerance were monitored at alpine sites and at a site distinctly below the natural distribution boundary, where higher temperatures were expected. The range of heat tolerance limits in summer, 45.5 - 54.5 °C (9 K), exceeded that reported for other alpine species (0.1 - 5 K) and even that for total seasonal changes (5 - 8 K). Heat tolerance either increased or decreased on most days (80 %). The maximum diurnal increase was + 4.7 K. Under the experimental conditions heat hardening started at leaf temperatures around 30 °C and proceeded at mean rates of 1.0 ± 0.5 K/h. The onset of functional disturbances in photosystem II also occurred at 30 °C. Heating rates exceeding those naturally found above 30 °C (> 10 K/h) appeared to retard heat hardening. During summer average leaf temperature maxima were 12.4 K (600 m) and 13.0 K (1945 m) higher than air temperature which corroborates the heat trapping nature of cushion plants. At 600 m, as compared to 1945 m, cushions experienced significantly higher leaf temperature maxima (+ 8.8 K) and exceeded 30 °C on most days (80 %). This resulted in a significantly higher heat tolerance (LT50) at 600 m (51.7 ± 0.2 °C) than at 1945 m (49.8 ± 0.2 °C). The fast short-term changes of heat tolerance in summer help S. acaulis to cope with the occasional diurnal short-term heat stress associated with cushion growth. [source] Psychosocial adjustment of siblings of children with cancer: a systematic reviewPSYCHO-ONCOLOGY, Issue 8 2010Melissa A. Alderfer Abstract Objectives: To promote a broader understanding of the psychosocial impact of childhood cancer on siblings, a systematic review was undertaken. Directions for future research are proposed and clinical strategies are suggested for addressing the needs of these children. Methods: Searches of Medline, PsycINFO and CINAHL revealed 65 relevant qualitative, quantitative, or mixed methods' papers published between 1997 and 2008. These papers were rated for scientific merit and findings were extracted for summary. Results: Siblings of children with cancer do not experience elevated mean rates of psychiatric disorders, but a significant subset experiences post-traumatic stress symptoms, negative emotional reactions (e.g. shock, fear, worry, sadness, helplessness, anger, and guilt), and poor quality of life in emotional, family, and social domains. In general, distress is greater closer to time of diagnosis. School difficulties are also evident within 2 years of diagnosis. Qualitative studies reveal family-level themes such as loss of attention and status as well as positive outcomes including increased sibling maturity and empathy. Conclusions: Research regarding siblings of children with cancer continues to be methodologically limited. The conclusions of qualitative and quantitative studies differ considerably. We propose a research agenda to propel this field forward including greater attention to alterations in normative development (as opposed to psychiatric conditions), development of more appropriate quantitative measures, examination of potential moderators of adaptation, and use of prospective longitudinal designs. Siblings of children with cancer are a psychosocially at-risk group and should be provided with appropriate supportive services. Copyright © 2009 John Wiley & Sons, Ltd. [source] Feasibility of randomized controlled trials in liver surgery using surgery-related mortality or morbidity as endpoint,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 9 2009M. A. J. van den Broek Background: There is a shortage of randomized controlled trials (RCTs) on which to base guidelines in liver surgery. The feasibility of conducting an adequately powered RCT in liver surgery using the dichotomous endpoints surgery-related mortality or morbidity was examined. Methods: Articles published between January 2002 and November 2007 with mortality or morbidity after liver surgery as primary endpoint were retrieved. Sample size calculations for a RCT aiming to show a relative reduction of these endpoints by 33, 50 or 66 per cent were performed. Results: The mean operative mortality rate was 1·0 per cent and the total morbidity rate 28·9 per cent; mean rates of bile leakage and postresectional liver failure were 4·4 and 2·6 per cent respectively. The smallest numbers of patients needed in each arm of a RCT aiming to show a 33 per cent relative reduction were 15 614 for operative mortality, 412 for total morbidity, 3446 for bile leakage and 5924 for postresectional liver failure. Conclusion: The feasibility of conducting an adequately powered RCT in liver surgery using outcomes such as mortality or specific complications seems low. Conclusions of underpowered RCTs should be interpreted with caution. A liver surgery-specific composite endpoint may be a useful and clinically relevant solution to pursue. Copyright © 2009 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] | ||||||||||||||||