A bacterial ratchet motor

Self-propelling bacteria are a dream of nano-technology. These unicellular organisms are not just capable of living and reproducing, but they can swim very efficiently, sense the environment and look for food, all packaged in a body measuring a few microns. Before such perfect machines could be artificially assembled, researchers are beginning to explore new ways to harness bacteria as propelling units for micro-devices. Proposed strategies require the careful task of aligning and binding bacterial cells on synthetic surfaces in order to have them work cooperatively. Here we show that asymmetric micro-gears can spontaneously rotate when immersed in an active bacterial bath. The propulsion mechanism is provided by the self assembly of motile Escherichia coli cells along the saw-toothed boundaries of a nano-fabricated rotor. Our results highlight the technological implications of active matter's ability to overcome the restrictions imposed by the second law of thermodynamics on equilibrium passive fluids.Comment: 4 pages, 3 figure

Prevalence of chronic kidney disease in Peruvian primary care setting.

Background: Chronic Kidney Disease (CKD) is a worldwide public health problem. There are few studies in Latin America, especially in primary care settings. Our objective was to determine the prevalence, stages, and associated factors of CKD in primary care setting. Methods: We did a retrospective secondary analysis of a database from the Diabetes and Hypertension Primary Care Center of the Peruvian Social Security System (EsSalud) in Lima, Peru. We defined CKD as the presence of eGFR 30 mg/day in 24 h, according to Kidney Disease: Improving Global Outcomes (KDIGO). Factors associated with CKD were evaluated with Poisson Regression models; these factors included age, gender, type 2 diabetes mellitus (DM2), hypertension (HTN), body mass index (BMI), and uric acid. Associations were described as crude and adjusted prevalence ratios (PR) and their 95% confidence intervals (95% CI). Results: We evaluated 1211 patients (women [59%], mean age 65.8 years [SD: 12.7]). Prevalence of CKD was 18%. Using the estimated glomerular filtration rate (eGFR), the prevalence was 9.3% (95% CI 5.3 – 13.3) in patients without HTN or DM2; 20.2% (95% CI 17.6 – 22.8) in patients with HTN, and 23.9% (95% CI 19.4 – 28.4) in patients with DM2. The most common stages were 1 and 2 with 41.5% and 48%, respectively. Factors associated with CKD in the adjusted analysis were: age in years (PR = 1.03, 95% CI 1.01 – 1.04), DM2 (PR = 3.37, 95% CI 1.09 – 10.39), HTN plus DM2 (PR = 3.90, 95% CI 1.54 – 9.88), and uric acid from 5 to <7 mg/dL (PR = 2.04, 95% CI 1.31 – 3.19) and ≥7 mg/dL (PR = 5.19, 95% CI 3.32 – 8.11). Conclusions: Prevalence of CKD in the primary care setting population was high. CKD is more frequent in the early stages of the disease, and individuals with hypertension, DM2, older age and hyperuricemia have higher prevalence of CKD.Revisión por pare

In-hospital mortality among incident hemodialysis older patients in Peru.

BACKGROUND: Understanding the pattern of mortality linked to end stage renal disease (ESRD) is important given the increasing ageing population in low- and middle-income countries. METHODS: We analyzed older patients with ESRD with incident hemodialysis, from January 2012 to August 2017 in one large general hospital in Peru. Individual and health system-related variables were analyzed using Generalized Linear Models (GLM) to estimate their association with in-hospital all-cause mortality. Relative risk (RR) with their 95% confidence intervals (95% CI) were calculated. RESULTS: We evaluated 312 patients; mean age 69 years, 93.6% started hemodialysis with a transient central venous catheter, 1.7% had previous hemodialysis indication and 24.7% died during hospital stay. The mean length of stay was 16.1 days (SD 13.5). In the adjusted multivariate models, we found higher in-hospital mortality among those with encephalopathy (aRR 1.85, 95% CI 1.21-2.82 vs. without encephalopathy) and a lower in-hospital mortality among those with eGFR ≤7 mL/min (aRR 0.45, 95% CI 0.31-0.67 vs. eGFR>7 mL/min). CONCLUSIONS: There is a high in-hospital mortality among older hemodialysis patients in Peru. The presence of uremic encephalopathy was associated with higher mortality and a lower estimated glomerular filtration rate with lower mortality

Effect of Diacerein on Insulin Secretion and Metabolic Control in Drug-Naïve Patients With Type 2 Diabetes: A randomized clinical trial

OBJECTIVE - To assess the effect of diacerein on insulin secretion and metabolic control in drug-naïve patients with type 2 diabetes. RESEARCH DESIGN AND METHODS - A randomized, double-blind, placebo-controlled clinical trial was carried out in 40 drug-naïve adult patients with type 2 diabetes. A metabolic profile including interleukin (IL)-1β, tumor necrosis factor-a, IL-6, and fasting insulin levelswas carried out before the intervention and 2months afterward. A hyperglycemic-hyperinsulinemic clamp technique was performed to assess the phases of insulin secretion and insulin sensitivity. After randomization, 20 patients received diacerein (50mg once daily) for the first 15 days and twice daily for 45 additional days. The remaining patients received placebo. Intra- and intergroup differences were calculated by Wilcoxon signed rank and Mann-Whitney U tests. RESULTS-Therewere significant increases in first (102 ± 63 vs. 130 ± 75 pmol/L; P<0.01), late (219 ± 111 vs. 280 ± 135 pmol/L; P<0.01), and total insulin (178691 vs. 216699pmol/L; P<0.01) secretionswithout changes in insulin sensitivity after diacerein administration. There were significant decreases in fasting glucose (7.9 ± 1.4 vs. 6.8 ± 1.0mmol/L; P<0.01) and in A1C levels (8.3 ± 1.0 vs. 7.0 ± 0.8%; P < 0.001) after diacerein administration. There were no significant changes after placebo administration in the above-mentioned evaluations. CONCLUSIONS - Insulin secretion increased and metabolic control improved after diacerein administration in drug-naïve patients with type 2 diabetes. © 2011 by the American Diabetes Association

Multichannel Detrended Fluctuation Analysis Reveals Synchronized Patterns of Spontaneous Spinal Activity in Anesthetized Cats

The analysis of the interaction and synchronization of relatively large ensembles of neurons is fundamental for the understanding of complex functions of the nervous system. It is known that the temporal synchronization of neural ensembles is involved in the generation of specific motor, sensory or cognitive processes. Also, the intersegmental coherence of spinal spontaneous activity may indicate the existence of synaptic neural pathways between different pairs of lumbar segments. In this study we present a multichannel version of the detrended fluctuation analysis method (mDFA) to analyze the correlation dynamics of spontaneous spinal activity (SSA) from time series analysis. This method together with the classical detrended fluctuation analysis (DFA) were used to find out whether the SSA recorded in one or several segments in the spinal cord of the anesthetized cat occurs either in a random or in an organized manner. Our results are consistent with a non-random organization of the sets of neurons involved in the generation of spontaneous cord dorsum potentials (CDPs) recorded either from one lumbar segment (DFA- mean = 1.040.09) or simultaneously from several lumbar segments (mDFA- mean = 1.010.06), where  = 0.5 indicates randomness while 0.5 indicates long-term correlations. To test the sensitivity of the mDFA method we also examined the effects of small spinal lesions aimed to partially interrupt connectivity between neighboring lumbosacral segments. We found that the synchronization and correlation between the CDPs recorded from the L5 and L6 segments in both sides of the spinal cord were reduced when a lesion comprising the left dorsal quadrant was performed between the segments L5 and L6 (mDFA- = 0.992 as compared to initial conditions mDFA- = 1.186). The synchronization and correlation were reduced even further after a similar additional right spinal lesion (mDFA- = 0.924). In contrast to the classical methods, such as correlation and coherence quantification that define a relation between two sets of data, the mDFA method properly reveals the synchronization of multiple groups of neurons in several segments of the spinal cord. This method is envisaged as a useful tool to characterize the structure of higher order ensembles of cord dorsum spontaneous potentials after spinal cord or peripheral nerve lesions

Metodología para la restauración y puesta en marcha de una máquina fresadora CNC

The Computerized Numerical Control (CNC) is a technology that allows, through the use of a computer, to control and monitor the movements of a machine tool. The Superior Technological Institute of San Andrés Tuxtla (ITSSAT) has a CNC milling machine tool with European technology acquired by the state government in 2003 for engineering student practices. The machine was obsolete and out of operation, a situation that obligates not to use the CNC in practice for a while since the industries that manufacture them use licensed software and electronic cards that have a high cost for repair. The purpose of this article is to&nbsp;present a methodology for the restoration and start-up of CNC machines without having to resort to the manufacturer. The results show the methodology whose main function is the communication of the CNC machine with the PC through the implementation of the alternate software Mach 3 and the electronic card LPT-Mach 3 achieving the operation of the machine and the milling of materials with academic and industrial purposes.El Control Numérico Computarizado (CNC) es una tecnología que permite mediante el uso de una computadora controlar y monitorear los movimientos de una máquina herramienta. El Instituto Tecnológico Superior de San Andrés Tuxtla (ITSSAT) cuenta con una máquina herramienta fresadora CNC con tecnología europea adquirida por el gobierno del Estado en el 2003 para prácticas de los estudiantes de ingeniería. La máquina se encontraba obsoleta y sin funcionamiento, situación que provoco no hacer uso de la CNC en las prácticas durante un tiempo, ya que las industrias que las fabrican utilizan software con licencia y tarjetas electrónicas que tienen un costo elevado para su reparación. El presente artículo tiene como finalidad dar a conocer una metodología para la restauración y puesta en marcha de la máquina fresadora CNC sin necesidad de recurrir al fabricante. Los resultados muestran la metodología cuya principal función es la comunicación de la máquina CNC con la PC mediante la implementación del software alterno Mach 3 y la tarjeta electrónica LPT-Mach 3 logrando el funcionamiento de la máquina y con ello el fresado de materiales con fines académicos e industriales

Beneficial or detrimental activity of regulatory T cells, indoleamine 2,3-dioxygenase, and heme oxygenase-1 in the lungs is influenced by the level of virulence of Mycobacterium tuberculosis strain infection

Tuberculosis (TB) caused by the complex Mycobacterium tuberculosis (Mtb) is the main cause of death by a single bacterial agent. Last year, TB was the second leading infectious killer after SARS-CoV-2. Nevertheless, many biological and immunological aspects of TB are not completely elucidated, such as the complex process of immunoregulation mediated by regulatory T cells (Treg cells) and the enzymes indoleamine 2,3-dioxygenase (IDO) and heme oxygenase 1 (HO-1). In this study, the contribution of these immunoregulatory factors was compared in mice infected with Mtb strains with different levels of virulence. First Balb/c mice were infected by intratracheal route, with a high dose of mild virulence reference strain H37Rv or with a highly virulent clinical isolate (strain 5186). In the lungs of infected mice, the kinetics of Treg cells during the infection were determined by cytofluorometry and the expression of IDO and HO-1 by RT-PCR and immunohistochemistry. Then, the contribution of immune-regulation mediated by Treg cells, IDO and HO-1, was evaluated by treating infected animals with specific cytotoxic monoclonal antibodies for Treg cells depletion anti-CD25 (PC61 clone) or by blocking IDO and HO-1 activity using specific inhibitors (1-methyl-D,L-tryptophan or zinc protoporphyrin-IX, respectively). Mice infected with the mild virulent strain showed a progressive increment of Treg cells, showing this highest number at the beginning of the late phase of the infection (28 days), the same trend was observed in the expression of both enzymes being macrophages the cells that showed the highest immunostaining. Animals infected with the highly virulent strain showed lower survival (34 days) and higher amounts of Treg cells, as well as higher expression of IDO and HO-1 one week before. In comparison with non-treated animals, mice infected with strain H37Rv with depletion of Treg cells or treated with the enzymes blockers during late infection showed a significant decrease of bacilli loads, higher expression of IFN-g and lower IL-4 but with a similar extension of inflammatory lung consolidation determined by automated morphometry. In contrast, the depletion of Treg cells in infected mice with the highly virulent strain 5186 produced diffuse alveolar damage that was similar to severe acute viral pneumonia, lesser survival and increase of bacillary loads, while blocking of both IDO and HO-1 produced high bacillary loads and extensive pneumonia with necrosis. Thus, it seems that Treg cells, IDO and HO-1 activities are detrimental during late pulmonary TB induced by mild virulence Mtb, probably because these factors decrease immune protection mediated by the Th1 response. In contrast, Treg cells, IDO and HO-1 are beneficial when the infection is produced by a highly virulent strain, by regulation of excessive inflammation that produced alveolar damage, pulmonary necrosis, acute respiratory insufficiency, and rapid death

Hydrodynamic Synchronisation of Model Microswimmers

We define a model microswimmer with a variable cycle time, thus allowing the possibility of phase locking driven by hydrodynamic interactions between swimmers. We find that, for extensile or contractile swimmers, phase locking does occur, with the relative phase of the two swimmers being, in general, close to 0 or pi, depending on their relative position and orientation. We show that, as expected on grounds of symmetry, self T-dual swimmers, which are time-reversal covariant, do not phase-lock. We also discuss the phase behaviour of a line of tethered swimmers, or pumps. These show oscillations in their relative phases reminiscent of the metachronal waves of cilia.Comment: 17 pages, 8 figure

The Effectiveness of Fiscal Policy in Mexico

Using a VAR model with quarterly information for the 1980 to 2008 period, this paper studies the dynamic effects of fiscal policy on Gross Domestic Product in the Mexican economy. We find evidence of non–Keynesian effects of government expenditure on GDP in the short run. Also, we find evidence that government revenue has a significant impact on GDP only in the fourth quarter

The Effectiveness of Fiscal Policy in Mexico

Using a VAR model with quarterly information for the 1980 to 2008 period, this paper studies the dynamic effects of fiscal policy on Gross Domestic Product in the Mexican economy. We find evidence of non–Keynesian effects of government expenditure on GDP in the short run. Also, we find evidence that government revenue has a significant impact on GDP only in the fourth quarter