Parental factors in dominance of lateral buds on rhizomes of Agropyron repens (L.) beauv.

Summary A mixture of 1-naphthylacetic acid and 6-benzylaminopurine was found to be an effective substitute for the rhizome apex of attached rhizomes, when the plants were not at anthesis. The same mixture was not effective, however, when the plants were at anthesis. The same growth-regulators applied to the apical end of detached multi-node rhizome fragments did not maintain correlative inhibition unless growth-regulators were simultaneously applied to the basal end. Various interactions between apical and basal applications are discussed with regard to their role as a parental factor in apical dominance.Abbreviations NAA 1-naphthyl acetic acid - BAP 6-benzylaminopurine - ABA abcisic acid - IAA indole-3-acetic acid     

Exploring New Areas: How Important is Long-Term Spatial Memory for Mangabey (<Emphasis Type="BoldItalic">Lophocebus albigena johnstonii</Emphasis>) Foraging Efficiency?

Studies of primate foraging efficiency during the exploration of new areas can provide important insights into the adaptive value of long-term spatial memory. After 6 yr of observation of a group of gray-cheeked mangabeys (Lophocebus albigena johnstonii) in Kibale National Park, Uganda, we observed exploration of a new area, followed 7 mo later by a group split. We recorded their ranging and foraging behavior for 22 mo after the first exploration. Controlling for weather variables, we found that mangabeys moved longer daily travel distances, explored more area per day, and had larger group spreads in the new area compared to the old area in both parent and daughter groups. The increase in search swath in the new area likely enabled the monkeys to counteract their lack of knowledge of food locations in the new area, as the efficiency in finding fruit in general did not differ between the old and new areas. We did, however, find a lower efficiency in finding fruit from preferred fig trees whose edibility could not be assessed by visual cues in the new area. Fig finding efficiency remained lower, even when we controlled for potential differences in fig density. In addition, mangabeys traveled and foraged less often on the ground in the new compared to the old area. However, when the monkeys became more familiar with the new area, terrestrial behavior increased. Our results are consistent with the hypothesis that when monkeys move into an area in which they have no experience, an absence of knowledge acquired via long-term spatial memory decreases their foraging efficiency.     

Surgical Management of Tibial Bone Loss in Revision Total Knee Arthroplasty: Clinical Outcomes and Radiographic Analysis of Tantalum Cones,Titanium Cones and Titanium Sleeves

BackgroundThe use of metaphyseal cones and sleeves has improved the ability to manage tibial bone loss in revision total knee arthroplasty (TKA). The purpose of this study was to compare the outcomes of three systems used for tibial metaphyseal reconstruction in revision TKA.MethodsWe performed a retrospective review of a consecutive series of 723 revision TKAs, including 145 (20%) knee revisions using tibial cones or sleeves. We compared porous tantalum (TM) cones, titanium (Ti) cones and titanium sleeves. The mean follow-up was 2.5 years.ResultsThe rate of revision for any reason was similar among all groups. Revision-free survival rates were similar among all systems studied at a mean follow-up of 2.5 years (TM cones 93%, Ti cones 94%, titanium sleeves 89%). Ti cones had a lower complication rate (6%) compared to TM cones (24%) and sleeves (29%). TM cones (15%) and titanium sleeves (13%) had higher reoperation rates (for any cause) than Ti cones (2%). Radiographic loosening was higher for sleeves (11%) than TM and Ti cones (2%).ConclusionMetaphyseal reconstruction for tibial bone loss in revision TKA using tantalum cones, titanium cones and titanium sleeves showed successful and comparable early clinical outcomes at a mean follow-up of 2.5 years with higher rates of radiographic loosening for titanium sleeves. Level of Evidence: III     

Early molecular-level changes in rat bladder wall tissue following spinal cord injury

Previously, we demonstrated using a rat model of spinal cord injury (SCI) that bladder wall tissue compliance significantly increased within the first 2 weeks following injury. In order to explore the potential molecular-level mechanisms of this event, the present study quantified molecules pertinent to bladder tissue remodeling and changes in mechanical properties. An initial gene array analysis followed by real-time qPCR revealed that the message levels for tropoelastin and lysyl oxidase were as high as 8-fold in SCI rats compared to normal. Furthermore, both the message and protein levels of TGF-beta1 and IGF-1, known stimulators of elastin synthesis, in SCI rat bladders were significantly higher compared to those of normal rats. Taken together, it can be speculated that functional changes of the bladder associated with SCI induce release of select growth factors, which, in turn, stimulate elastogenesis that lead to alteration of biomechanical properties of the wall tissue.     

Eastern chimpanzees, but not bonobos, represent a simian immunodeficiency virus reservoir

Chimpanzees in west central Africa (Pan troglodytes troglodytes) are endemically infected with simian immunodeficiency viruses (SIVcpzPtt) that have crossed the species barrier to humans and gorillas on at least five occasions, generating pandemic and nonpandemic forms of human immunodeficiency virus type 1 (HIV-1) as well as gorilla SIV (SIVgor). Chimpanzees in east Africa (Pan troglodytes schweinfurthii) are also infected with SIVcpz; however, their viruses (SIVcpzPts) have never been found in humans. To examine whether this is due to a paucity of natural infections, we used noninvasive methods to screen wild-living eastern chimpanzees in the Democratic Republic of the Congo (DRC), Uganda, and Rwanda. We also screened bonobos (Pan paniscus) in the DRC, a species not previously tested for SIV in the wild. Fecal samples (n = 3,108) were collected at 50 field sites, tested for species and subspecies origin, and screened for SIVcpz antibodies and nucleic acids. Of 2,565 samples from eastern chimpanzees, 323 were antibody positive and 92 contained viral RNA. The antibody-positive samples represented 76 individuals from 19 field sites, all sampled north of the Congo River in an area spanning 250,000 km(2). In this region, SIVcpzPts was common and widespread, with seven field sites exhibiting infection rates of 30% or greater. The overall prevalence of SIVcpzPts infection was 13.4% (95% confidence interval, 10.7% to 16.5%). In contrast, none of the 543 bonobo samples from six sites was antibody positive. All newly identified SIVcpzPts strains clustered in strict accordance to their subspecies origin; however, they exhibited considerable genetic diversity, especially in protein domains known to be under strong host selection pressure. Thus, the absence of SIVcpzPts zoonoses cannot be explained by an insufficient primate reservoir. Instead, greater adaptive hurdles may have prevented the successful colonization of humans by P. t. schweinfurthii viruses.     

Toward in situ biochemistry: combining chemical kinetics approaches with biomolecular imaging in living cells

Our knowledge of protein-protein interactions comes primarily from experimentation with reconstituted proteins in dilute solutions. However, dilute solutions are poor approximations of the intracellular microenvironment, which contains exquisite and dynamic structure that is impossible to recreate inside test tubes. New approaches are needed that will allow the in situ characterization of protein-protein interactions inside living, intact cells. In this paper, we discuss recent efforts to measure the kinetics of protein binding within complexes inside living cells. While the experimental effort in these studies requires the confluence of techniques ranging from molecular imaging to cell and molecular biology, the experimental design and analysis requires a strong background in chemical kinetics and transport phenomena. Thus, we argue that chemical engineers can play a central role in furthering in situ approaches to cellular analysis. Such efforts may aid significantly in advancing quantitative knowledge of cellular signaling and physiology.     

Carotid geometry effects on blood flow and on risk for vascular disease

It has been widely observed that atherosclerotic diseases occur at sites with complex hemodynamics, such as artery bifurcations, junctions, and regions of high curvature. These regions usually have very low or highly oscillatory wall shear stress (WSS). In the present work, 3D pulsatile blood flow through a model of the carotid artery bifurcation was simulated using a finite volume numerical method. The goal was to quantify the risk of atherogenesis associated with different carotid artery geometries. A risk scale based on the average WSS on the sinus wall of the internal carotid artery was proposed-a scale that can be used to quantify the effect of the carotid geometry on the relative risk for developing vascular disease. It was found that the bifurcation angle and the out-of-plane angle of the internal carotid artery affect the formation of low stress regions on the carotid walls. The main conclusions are: (a) larger internal carotid artery angles (theta(IC)) generally increase the frequency and the area of blood recirculation and lower the WSS on the sinus wall, hence increasing the risk of plaque build-up; (b) off-plane angles were found to lower the WSS on the sinus for geometries with theta(IC)25 degrees . Larger off-plane angles generally increase the danger of plague build-up; (c) for theta(IC) < 25 degrees , the off-plane angle does not have an obvious effect on the hemodynamic WSS; (d) symmetric bifurcations were found to increase the WSS on the sinus wall and ease the risk of vascular disease.