Overwhelming Number (overwhelming + number)

Distribution by Scientific Domains

Selected Abstracts

Fallacies of High-Speed Hemodialysis

Zbylut J. Twardowski
Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra- and interdialytic symptoms. Financial and logistical pressures related to the overwhelming number of patients requiring hemodialysis created an incentive to shorten dialysis time to four, three, and even two hours per session in a thrice weekly schedule. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/Vurea) equals 0.95,1.0. This number was later increased to 1.3, but the assumption remained unchanged that hemodialysis time is of minimal importance as long as it is compensated by increased urea clearance. Patients accepted short dialysis as a godsend, believing that it would not be detrimental to their well-being and longevity. However, Kt/Vurea measures only removal of low molecular weight substances and does not consider removal of larger molecules. Besides, it does not correlate with the other important function of hemodialysis, namely ultrafiltration. Whereas patients with substantial residual renal function may tolerate short dialysis sessions, the patients with little or no urine output tolerate short dialyses poorly because the ultrafiltration rate at the same interdialytic weight gain is inversely proportional to dialysis time. Rapid ultrafiltration is associated with cramps, nausea, vomiting, headache, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control, left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Short, high-efficiency dialysis requires high blood flow, which increases demands on blood access. The classic wrist arteriovenous fistula, the access with the best longevity and lowest complication rates, provides "insufficient" blood flow and is replaced with an arteriovenous graft fistula or an intravenous catheter. Moreover, to achieve high blood flows, large diameter intravenous catheters are used; these fit veins "too tightly," so predispose the patient to central-vein thrombosis. Longer hemodialysis sessions (5,8 hrs, thrice weekly), as practiced in some centers, are associated with lower complication rates and better outcomes. Frequent dialyses (four or more sessions per week) provide better clinical results, but are associated with increased cost. It is my strong belief that a wide acceptance of longer, gentler dialysis sessions, even in a thrice weekly schedule, would improve overall hemodialysis results and decrease access complications, hospitalizations, and mortality, particularly in anuric patients. [source]

Designs for greenhouse studies of interactions between plants: an analytical perspective

R. P. Freckleton
Summary 1,Experiments on competition between plant species are frequently designed without considering the analysis stage of the study. We argue that this omission may lead to over-complication of the issue of designing experiments. 2,An overwhelming number of studies have shown that the effects on performance of competition in plant mixtures may be described by simple (hyperbolic) regression models. The most natural view of the problem of measuring plant competition is therefore as a problem in regression. 3,Only with experiments designed explicitly to apply regression analyses can phenomena such as frequency dependence and the size dependence of measures of competition be identified. In contrast to previous assertions, this means that designs that are based around, or allow, regression analysis are the most robust as such effects may be tested for using appropriate statistics. 4,Experiments are probably most easily designed to measure competition as a function of the density of interacting species, rather than biomass. This is because the per unit biomass effect of competition on performance is a function of density. Competition measures based on biomass will hence be dependent on the density at which the experiment is performed. Furthermore, the most effective way to manipulate biomass is through changing species' densities. 5,In terms of economy of design, we would recommend simple additive series. Whilst this does not allow the role of frequency dependence to be analysed, this phenomenon appears to be rare in any case. [source]

A set of 16 consensus primer pairs amplifying the complete mitochondrial genomes of orange-spotted grouper (Epinephelus coioides) and Hong Kong grouper (Epinephelus akaara)

Abstract Groupers are of considerable economic value; however, their classification and evolutionary relationships have long been hindered by the overwhelming number of species and lack of morphological specializations. Mitochondrial genome is a source of original markers that are potentially useful in the study of phylogeny and population genetics of groupers. We describe a set of 16 new primer pairs that allow PCR amplification of the entire mitochondrial genomes of orange-spotted grouper and Hong Kong grouper. This primer set has been defined for consensus over eight other grouper species, facilitating further studies on the molecular evolution and population genetics of groupers. [source]

Is there pre-attentive memory-based comparison of pitch?

Thomas Jacobsen
The brain's responsiveness to changes in sound frequency has been demonstrated by an overwhelming number of studies. Change detection occurs unintentionally and automatically. It is generally assumed that this brain response, the so-called mismatch negativity (MMN) of the event-related brain potential or evoked magnetic field, is based on the outcome of a memory-comparison mechanism rather than being due to a differential state of refractoriness of tonotopically organized cortical neurons. To the authors' knowledge, however, there is no entirely compelling evidence for this belief. An experimental protocol controlling for refractoriness effects was developed and a true memory-comparison-based brain response to pitch change was demonstrated. [source]

T-cell recognition of a prostate specific antigen is not sufficient to induce prostate tissue destruction

THE PROSTATE, Issue 6 2006
Jason R. Lees
Abstract METHODS The ability of CD8+ T-cells to induce prostate inflammation was examined using a prostate ovalbumin expressing transgenic mouse (POET) and/or adoptive transfer of T-cell receptor (TCR) transgenic T-cells (OT-I) that specifically recognize ovalbumin. Localization of inflammatory cells to prostate tissue was examined following T-cell activation via endogenous prostatic antigen, recombinant type 5 adenovirus carrying the gene coding ovalbumin (Ad5-mOVA), or adoptive transfer of in vitro antigen stimulated OT-I cells. RESULTS Ovalbumin specific OT-I cells were activated by autologous prostate antigen and trafficked to the prostate, but did not induce inflammation unless present in overwhelming numbers (,65% of CD8+ T-cells). Activation of antigen specific CD8+ T-cells in vitro (peptide pulsed antigen presenting cells) or in vivo (Ad5-mOVA) induced transitory prostate inflammation, without induction of prostate pathology, regardless of CD4+ T-cell availability. Inflammation also was observed in OT-I,,POET mice but again, pathological effects were not observed. CONCLUSIONS T lymphocytes specific for a prostate antigen are capable of inducing inflammatory infiltration of prostatic tissue rapidly following activation, but do not produce pathological prostate injury. Prostate 66:578,590, 2006. 2005 Wiley-Liss, Inc. [source]

An Improvised Oxygen Supply System for Pandemic and Disaster Use

Charles M. Little DO
Abstract Background:, Current disaster planning for pandemic influenza anticipates overwhelming numbers of patients in need of hospitalization. The anticipated use of extra, or "surge," beds is common in both hospital and community disaster response planning. In a pandemic of respiratory illness, supplemental oxygen will be a life-saving intervention. There are currently few options to provide these proposed surge beds with the necessary oxygen. Objectives:, A method of providing an improvised oxygen delivery system for use in a disaster was developed and tested. This system was designed to use readily available commercial materials to assemble an oxygen delivery system. Methods:, The study consisted of a laboratory design, assembly, and testing of an improvised oxygen system. Results:, A liquid oxygen (LOX) Dewar container was used to supply oxygen systems built from inexpensive commercially available plastic tubing and fittings. The system will drive ventilators without significant pressure drop or ventilator malfunction. The final developed system will supply 30 patients with up to 6 L/min (l pm) oxygen each by nasal cannula from a single oxygen Dewar. Conclusions:, An improvised system to deliver oxygen for patient beds or ventilator use can be easily assembled in the event of a disaster. This could be life-saving in the event of a pandemic of respiratory illness. [source]