Inhibition of bacterial growth through LED (light-emitting diode) 465 and 630 nm: in vitro

Lasers in Medical Science - Photobiomodulation has been used to inactivate bacterial growth, in different laser or LED protocols. Thus, the aim of this study was to verify the inhibition of...     

Case for staged thyroidectomy

Recent modifications in the management of well‐differentiated thyroid cancer have resulted in significant alterations in clinical approach. Utilizing a series of preoperative and postoperative risk factors involving both the patient and the disease pathology, we offer the term “staged thyroidectomy” to help organize these risk factors for patients and the endocrine team to optimize management. This approach is intended to incorporate our latest nuanced understanding of certain endocrine pathology and may serve to optimize patient outcomes.     

Glycemic control in elderly people with type 2 diabetes mellitus attending primary health care units

AimTo assess the glycemic control in elderly people with type 2 diabetes mellitus who attend the primary health care units in the city of Ribeirão Preto, State of São Paulo, Brazil.MethodsThis is a cross-sectional study with elderly people registered at the family health care system. Glycemic control was the dependent variable, which was measured by means of glycated hemoglobin test, whereas sociodemographic and clinical data were independent variables.Results243 elderly people participated in the study, with the majority being females (67.1%), Caucasian (58.4%), within the age group of 60?69 years old (53.9%) and less than four years of study (74.9%). The mean glycated hemoglobin test was 7.2% (SD = 1.7). It was observed that 74.1% of the subjects had glycated hemoglobin test lower than 8.0%. A positive association between glycemic control and combined use of oral anti-diabetic drugs plus insulin was evidenced, whereas presence of cardiovascular disease, ulcer and amputation of lower extremities were the negative associations.ConclusionThe combined use of oral anti-diabetic drugs plus insulin was associated with adequate glycemic control in this elderly population. Among those who reported having a diabetic chronic complication, that is those who needed a stricter diabetes control, was observed a higher frequency of poor glycemic control. These findings are relevant in the primary care context to guide health care and interventions to achieve success in diabetes control.     

The Widened Pipe Model of plant hydraulic evolution

Shaping global water and carbon cycles, plants lift water from roots to leaves through xylem conduits. The importance of xylem water conduction makes it crucial to understand how natural selection deploys conduit diameters within and across plants. Wider conduits transport more water but are likely more vulnerable to conduction-blocking gas embolisms and cost more for a plant to build, a tension necessarily shaping xylem conduit diameters along plant stems. We build on this expectation to present the Widened Pipe Model (WPM) of plant hydraulic evolution, testing it against a global dataset. The WPM predicts that xylem conduits should be narrowest at the stem tips, widening quickly before plateauing toward the stem base. This universal profile emerges from Pareto modeling of a trade-off between just two competing vectors of natural selection: one favoring rapid widening of conduits tip to base, minimizing hydraulic resistance, and another favoring slow widening of conduits, minimizing carbon cost and embolism risk. Our data spanning terrestrial plant orders, life forms, habitats, and sizes conform closely to WPM predictions. The WPM highlights carbon economy as a powerful vector of natural selection shaping plant function. It further implies that factors that cause resistance in plant conductive systems, such as conduit pit membrane resistance, should scale in exact harmony with tip-to-base conduit widening. Furthermore, the WPM implies that alterations in the environments of individual plants should lead to changes in plant height, for example, shedding terminal branches and resprouting at lower height under drier climates, thus achieving narrower and potentially more embolism-resistant conduits.

Water transport through plants is a key driver of the carbon and other biogeochemical cycles (1–3) and is a crucial link in plant adaptation to climate and vegetation response to climate change (4–9). The water conducting cells of plants, xylem conduits, widen with distance from the stem tip, and, therefore, taller plants have wider conduits (6, 10–12). Xylem conduits are of two main types: tracheids, found in most gymnosperms, and vessels, found in most flowering plants. Tracheids have intact cell membranes, so water must flow from cell to cell through these membranes. Vessels are made up of cells aligned vertically end to end, with the cell membranes dissolved between successive members, forming a tube. Whatever their differences in structure, wider conduits are beneficial because they conduct more water. Tip-to-base widening is expected to help maintain conductance per unit leaf area constant as an individual plant grows taller, counterbalancing the resistance that would otherwise accrue with increasing conductive path length the individual grows (2, 13). Wider conduits, however, are more vulnerable to embolisms caused by cold and likely drought (8, 14–18) and cost more in terms of carbon for a plant (ref. 1; cf. ref. 19). Embolisms in the xylem even affect transport of photosynthates in the phloem (8, 20). This means that as trees grow taller, conductance, embolism vulnerability, and carbon costs must interrelate in a delicate evolutionary balance.Because of the importance of this balance in plant hydraulic evolution and in forest reactions to climate change (3, 6, 21–23), an important goal of plant biology is to construct models that predict how and why plants deploy conduit diameters throughout their bodies (1, 2, 17, 24–26). Some models predict that conduits should be of uniform diameter (27, 28), while others predict that they should widen tip to base (1, 2, 13, 24, 29, 30). But even current models include untested assumptions and large numbers of parameters, making it difficult to identify the biological causes of the predictions they make. For example, some invoke Da Vinci’s rule, the largely untested assumption that the summed wood area of the twigs is the same as that at the base (24, 26). Other models depict plant conduits as branching as they do in mammalian circulatory systems, but whether this happens along the entire stem in plants is unclear (30–33). There is an expectation that conduit diameter D should widen with distance from the stem tip L following a power-law (D ∝ L^b), but there is no agreement on the value of b, the conduit widening exponent (1, 2). Furthermore, even though within-individual tip-to-base conduit widening has been confirmed in a handful of species (34–36), and the scaling of conduit diameter with plant size across species is consistent with it (6, 10–12, 34), the expectation that conduits should widen similarly within stems across terrestrial vascular plant lineages and habits has yet to be empirically confirmed. Here we present the Widened Pipe Model (WPM), which correctly predicts the form of tip-to-base conduit widening across the span of plant size, life form, and habitat across the terrestrial plant phylogeny.     

Supply-demand balance and metabolic scaling

It is widely accepted that metabolic rates scale across species approximately as the 3/4 power of mass in most if not all groups of organisms. Metabolic demand per unit mass thus decreases as body mass increases. Metabolic rates reflect both the ability of the organism's transport system to deliver metabolites to the tissues and the rate at which the tissues use them. We show that the ubiquitous 3/4 power law for interspecific metabolic scaling arises from simple, general geometric properties of transportation networks constrained to function in biological organisms. The 3/4 exponent and other observed scaling relationships follow when mass-specific metabolic demands match the changing delivery capacities of the network at different body sizes. Deviation from the 3/4 exponent suggests either inefficiency or compensating physiological mechanisms. Our conclusions are based on general arguments incorporating the minimum of biological detail and should therefore apply to the widest range of organisms.     

Plasma erythropoietin levels in anaemic and non-anaemic patients with chronic liver diseases

AIM: To investigate the serum erythropoietin (Epo) levels in patients with chronic liver diseases and to compare to subjects with iron-deficiency anaemia and healthy controls. METHODS: We examined 31 anaemic (ALC) and 22 non-anaemic (NALC) cirrhotic patients, 21 non- anaemic subjects with chronic active hepatitis (CAH), 24 patients with iron-deficiency anaemia (ID) and 15 healthy controls. Circulating Epo levels (ELISA; R and D Systems, Europe Ltd, Abingdon, UK) and haemoglobin (Hb) concentration were determined in all subjects. RESULTS: Mean+/-SD of Epo values was 26.9+/-10.8 mU/mL in ALC patients, 12.5+/-8.0 mU/mL in NALC subjects, 11.6+/-6.3 mU/mL in CAH patients, 56.4+/-12.7 mU/mL in the cases of ID and 9.3+/-2.6 mU/mL in controls. No significant difference (P>0.05) was found in Epo levels between controls, CAH and NALC patients. ALC individuals had higher Epo levels (P<0.01) than these groups whereas ID subjects had even higher levels (P<0.001) than patients suffering from ALC. CONCLUSION: Increased Epo values in cirrhotics, are only detectable when haemoglobin was lesser than 12 g/dL. Nevertheless, this rise in value is lower than that observed in anaemic patients with iron-deficiency and appears blunted and inadequate in comparison to the degree of anaemia.     

Endothelial adhesion molecules ICAM-1, VCAM-1 and E-selectin in patients with acute coronary syndrome

INTRODUCTION AND OBJECTIVES: The acute inflammatory response is an important phenomenon in the pathogenesis of myocardial damage during acute coronary syndrome. Endothelial dysfunction has been found in unstable angina and acute myocardial infarction, although the results are controversial. The purpose of this study was to determine the levels of the soluble endothelial adhesion molecules ICAM-1, VCAM-1 and E-selectin, in patients with unstable angina and acute myocardial infarction, compare the results in both groups, and analyze their relation with the degree of myocardial injury. METHODS: Serum concentrations of ICAM-1, VCAM-1, and E-selectin were measured in 37 control subjects and 43 patients (32 with acute myocardial infarction and 11 with unstable angina). Measurements were made at the time of admission and ten days later using commercial enzyme-linked immunoabsorbent assay (ELISA) kits (R&D Systems, UK). RESULTS: There was a significant increase in E-selectin (p < 0.05) in patients with unstable angina at admission and ten days later. In contrast, patients with acute myocardial infarction showed no significant differences in E-selectin compared with the control group at admission or ten days later. A significant increase in VCAM-1 levels was demonstrated in both groups of patients and ICAM-1 levels in acute myocardial infarction, but the concentrations of VCAM-1 and ICAM-1 in both groups of patients at admission and ten days later did not differ significantly. There was no relation between soluble endothelial adhesion molecule levels and the severity of myocardial damage estimated by cardiac enzymes or electrocardiographic changes. CONCLUSION: This study indicates that serum levels of E-selectin, measured at time of admission and ten days later, could be a marker for unstable angina and might be useful in the differential diagnosis with myocardial infarction.     

Form,function, and evolution of living organisms

Despite the vast diversity of sizes and shapes of living organisms, life’s organization across scales exhibits remarkable commonalities, most notably through the approximate validity of Kleiber’s law, the power law scaling of metabolic rates with the mass of an organism. Here, we present a derivation of Kleiber’s law that is independent of the specificity of the myriads of organism species. Specifically, we account for the distinct geometries of trees and mammals as well as deviations from the pure power law behavior of Kleiber’s law, and predict the possibility of life forms with geometries intermediate between trees and mammals. We also make several predictions in excellent accord with empirical data. Our theory relates the separate evolutionary histories of plants and animals through the fundamental physics underlying their distinct overall forms and physiologies.Understanding the origin and evolution of the geometries of living forms is a formidable challenge (1, 2). The geometry of an object can be characterized by its surface−volume relationship—the surface area S of an object of volume V can scale at most as and at least as (3). These geometries have been used by nature in space-filling trees and animals, respectively. Here, our principal goal is to explore how it is that both geometries of life coexist on Earth, whether intermediate geometries are possible, and what all this implies for evolution of life on Earth.Living organisms span an impressive range of body mass, shapes, and scales. They are inherently complex, they have been shaped by history through evolution and natural section, and they continually extract, transform, and use energy from their environment. The most prevalent large multicellular organisms on Earth, namely plants and animals, exhibit distinct shapes, as determined by the distribution of mass over the volume. Animals are able to move and are approximately homogeneous in their mass distribution—yet they have beautiful fractal transportation networks. Plants are rooted organisms with a heterogeneous self-similar (fractal) geometry—the mass of the tree is more concentrated in the stem and branches than in the leaves.The approximate power law dependence of the metabolic rate, the rate at which an organism burns energy, on organism mass has been carefully studied for nearly two centuries and is known as allometric scaling (4–32). From the power law behavior, with an exponent around 3/4, one can deduce the scaling of characteristic quantities with mass and, through dimensional analysis, obtain wide-ranging predictions often in accord with empirical data. However, what underlies this ubiquitous quarter-power scaling, and with a dominant exponent of 3/4?In an influential series of papers, West and coworkers (11, 12, 14–16) suggested that fractality was at the heart of allometric scaling. Inspired by these papers, a contrasting view was presented (13), which argued that, although fractal circulatory networks may have advantages, quarter-power scaling came built in with the directed transport of nutrients. However, this latter paper was necessarily incomplete because it did not address the distinct geometries of animals and trees. More recently, members of both groups joined together to construct explicit models for animals, which showed (24) that “quarter-power scaling can arise even when there is no underlying fractality.” Here, we take a fresh look at the problem and derive quarter-power scaling quite generally for all living organisms. We then turn to a consideration of the sharp differences in the geometries of animals and trees and argue that the evolution of organismal forms follows from a rich interplay of geometry, evolutionary history, developmental symmetry, and efficient nutrient acquisition.Despite their independent evolution and different metabolisms, vascular plants and bilaterian animals share major design features, namely, an internal mass comprising organized cells capable of metabolic and bioenergetic activities, a transport mechanism for distributing molecules and energy within itself, and a surface capable of exchanging matter and energy with the environment. Regardless of the shape differences observed between these two groups, the physics associated with the transformation, transport, and exchange of matter and energy must unavoidably impose physical constraints on their designs. An organism is akin to an engine—part of the energy obtained from nourishment is used for organism function, growth, reproduction, while the rest is dissipated through its surface. We consider the hypothesis of the survival of the fittest in terms of energy metabolism and postulate that an organism with a higher energy intake would have a competitive advantage over another organism of similar mass performing energetically suboptimally, and explore its consequences.Consider an isotropic 3D organism of spatial extent h whose volume V scales as . Generalization to organisms with distinct scaling along the three different directions is straightforward. We make the simplifying assumption that the consumption and metabolic activity is distributed uniformly in space and in time or suitable averaging is used. We denote the basal metabolic rate of the organism by B and its mass by M. B is a measure of the energy being delivered to the organism per unit time and ought to be proportional to the energy dissipated through its surface. There is no evidence of size selection in empirical data, and this lends support to the assumption that the efficiency of the engine is independent of the organism’s size. We will derive Kleiber’s law based on energy intake considerations and study the role of geometry, as captured in the surface−volume relationship, on considering the expelled energy.Our goal is to understand the ideal dependence of B on M in the scaling regime. The characteristic time scale associated with the organism is known to scale as —it is a measure of how long it would take for energy proportional to M to be dissipated at a rate of B. Henceforth, proportionality constants, which serve to fix the correct units of various quantities related through scaling relations, will be omitted for the sake of simplicity.The number of metabolites, N, consumed in the organism per unit time is proportional to B. Let us define , so that a single metabolite is consumed per unit time in the local region surrounding each site of an grid. Each of these sites can be thought of as being within a service volume, in which one metabolite is consumed per unit time, of linear spatial extent . At the local level, the metabolites need to be transported this distance over unit time, and one immediately finds (24) that the transport velocity . Another measure of the transport velocity is obtained by noting that it is a characteristic length scale of the organism divided by the corresponding characteristic time scale and therefore scales as . Setting the two measures to be proportional to each other, one obtains Kleiber’s law .An alternative way of deriving the same result in a more rigorous manner is through the consideration of the properties of efficient transportation networks. The goal is to determine the minimum number of metabolites in transit, a measure of the organism mass, to ensure that metabolites are delivered in unit time within the organism volume. One can prove that the mass scales at least as with the optimality arising for efficient directed networks with no large-scale backtracking (13). This again leads to Kleiber’s law.Remarkably, the idealized metabolic rate−mass relationship is predicted to be algebraic with a exponent independent of the geometry of the organism. Such competitive equivalence explains the coexistence of animals with a homogeneous tissue density and fractal plants on Earth. The mass-specific metabolic rate, , scales as , whereas the transit time scales as . Indeed, characteristic biological rates (such as the heart beat and mutation rates) and characteristic biological times (such as circulation times or lifetimes) scale as and , respectively (6, 7, 9–12, 14–16).