Suplementación con concentrados con proteína no degradable en el rumen y el desempeño de vacas Holstein

Two experiments were conducted to determine the effects of level of concentrate supplementation with two concentrates differing in concentration and type of ruminally undegradable protein (RUP) on dry matter intake (DMI) and milk production of Holstein cows in late (E1) and early (E2) lactation. In both trials, concentrates were fed at the rate of 1 kg per 2.5 or 1.5 kg of milk, constituting low (LCS) and high (HCS) levels of concentrate supplementation, respectively. No significant effect of type of concentrate was observed on DMI, milk production, milk composition or efficiency of milk production in either experiment. HCS resulted in lower hay DM consumption by cows in late (9.8 vs. 11.3 kg/d) and early (6.4 vs. 8.1 kg/d) lactation, but also in greater total DMI by late (17.7 vs. 15.6 kg/d) and early (19.6 vs. 16.2 kg/d) lactation cows. Similarly, milk production was greater when late (13.1 vs. 11.8 kg/d) and early (25.5 vs. 22.6 kg/d) lactation cows were fed the HCS. In E2, contrary to E1, cows produced milk of higher fat concentration (2.66 vs. 3.18%) when the LCS was fed. HCS resulted in lower efficiency of concentrate use for milk and 3.25%-fat-corrected milk production, particularly during early lactation. However, income over feed cost was higher for HCS during early lactation. Thus, the practice of supplementing concentrates at a high level can be justified economically under conditions similar to those of this trial.Se realizaron dos experimentos para determinar los efectos del nivel de suplementación con dos concentrados con diferente concentración y tipo de proteína no degradable en el rumen (PND) en vacas Holstein en etapa tardía (E1) y etapa temprana (E2) de lactancia. En ambos estudios, los concentrados se suplieron a razón de 1 kg por cada 1.5 y 2.5 kg de leche, constituyendo los niveles alto (AS) y bajo (BS) de suplementación, respectivamente. Las diferencias en consumo de materia seca (MS), producción de leche, composición de la leche y eficiencia de la producción de leche debido al tipo de concentrado no fueron significativas (P < 0.05) en ninguno de los dos experimentos. El AS resultó en menor consumo de MS de heno en vacas en etapa tardía (9.8 vs. 11.3 kg/d) y temprana (6.4 vs. 8.1 kg/d) de lactancia, pero también resultó en mayor consumo de MS total en vacas en etapa tardía (17.7 vs. 15.6 kg/d) y temprana (19.6 vs. 16.2 kg/d) de lactancia. Igualmente, alimentar con AS resultó en mayor producción de leche en la etapa tardía (13.1 vs. 11.8 kg/d) y temprana (25.5 vs. 22.6 kg/d) de lactancia. En el E2, contrario al E1, la concentración de grasa láctea fue mayor con el BS (2.66 vs. 3.18%). Si bien AS resultó en una menor eficiencia del uso de concentrado para producir leche, particularmente en el E2, también aumentó el ingreso monetario sobre el costo de los alimentos en la lactancia temprana. Por consiguiente, el AS es justificable en términos económicos bajo condiciones similares a las de este estudio

Interaction between the Stress Phase Angle (SPA) and the Oscillatory Shear Index (OSI) Affects Endothelial Cell Gene Expression

Hemodynamic forces play an important role in the non-uniform distribution of atherosclerotic lesions. Endothelial cells are exposed simultaneously to fluid wall shear stress (WSS) and solid circumferential stress (CS). Due to variations in impedance (global factors) and geometric complexities (local factors) in the arterial circulation a time lag arises between these two forces that can be characterized by the temporal phase angle between CS and WSS (stress phase angle±SPA). Asynchronous flows (SPA close to -180Ê) that are most prominent in coronary arteries have been associated with localization of atherosclerosis. Reversing oscillatory flows characterized by an oscillatory shear index (OSI) that is great than zero are also associated with atherosclerosis localization. In this study we examined the relationship between asynchronous flows and reversing flows in altering the expression of 37 genes relevant to atherosclerosis development. In the case of reversing oscillatory flow, we observed that the asynchronous condition upregulated 8 genes compared to synchronous hemodynamics, most of them proatherogenic. Upregulation of the pro-inflammatory transcription factor NFκB p65 was confirmed by western blot, and nuclear translocation of NFκB p65 was confirmed by immunofluorescence staining. A comparative study between nonreversing flow and reversing flow found that in the case of synchronous hemodynamics, reversing flow altered the expression of 11 genes, while in the case of asynchronous hemodynamics, reversing flow altered the expression of 17 genes. Reversing flow significantly upregulated protein expression of NFκB p65 for both synchronous and asynchronous conditions. Nuclear translocation of NFκB p65 was confirmed for synchronous and asynchronous conditions in the presence of flow reversal. These data suggest that asynchronous hemodynamics and reversing flow can elicit proatherogenic responses in endothelial cells compared to synchronous hemodynamics without shear stress reversal, indicating that SPA as well as reversal flow (OSI) are important parameters characterizing arterial susceptibility to disease

High Glucose Attenuates Shear-Induced Changes in Endothelial Hydraulic Conductivity by Degrading the Glycocalyx

Diabetes mellitus is a risk factor for cardiovascular disease; however, the mechanisms through which diabetes impairs homeostasis of the vasculature have not been completely elucidated. The endothelium interacts with circulating blood through the surface glycocalyx layer, which serves as a mechanosensor/transducer of fluid shear forces leading to biomolecular responses. Atherosclerosis localizes typically in regions of low or disturbed shear stress, but in diabetics, the distribution is more diffuse, suggesting that there is a fundamental difference in the way cells sense shear forces. In the present study, we examined the effect of hyperglycemia on mechanotranduction in bovine aortic endothelial cells (BAEC). After six days in high glucose media, we observed a decrease in heparan sulfate content coincident with a significant attenuation of the shear-induced hydraulic conductivity response, lower activation of eNOS after exposure to shear, and reduced cell alignment with shear stress. These studies are consistent with a diabetes-induced change to the glycocalyx altering endothelial response to shear stress that could affect the distribution of atherosclerotic plaques

Permutation Invariant Parking Assortments

We introduce parking assortments, a generalization of parking functions with cars of assorted lengths. In this setting, there are $n\in\mathbb{N}$ cars of lengths $\mathbf{y}=(y_1,y_2,\ldots,y_n)\in\mathbb{N}^n$ entering a one-way street with $m=\sum_{i=1}^ny_i$ parking spots. The cars have parking preferences $\mathbf{x}=(x_1,x_2,\ldots,x_n)\in[m]^n$, where $[m]:=\{1,2,\ldots,m\}$, and enter the street in order. Each car $i \in [n]$, with length $y_i$ and preference $x_i$, follows a natural extension of the classical parking rule: it begins looking for parking at its preferred spot $x_i$ and parks in the first $y_i$ contiguously available spots thereafter, if there are any. If all cars are able to park under the preference list $\mathbf{x}$, we say $\mathbf{x}$ is a parking assortment for $\mathbf{y}$. Parking assortments also generalize parking sequences, introduced by Ehrenborg and Happ, since each car seeks for the first contiguously available spots it fits in past its preference. Given a parking assortment $\mathbf{x}$ for $\mathbf{y}$, we say it is permutation invariant if all rearrangements of $\mathbf{x}$ are also parking assortments for $\mathbf{y}$. While all parking functions are permutation invariant, this is not the case for parking assortments in general, motivating the need for a characterization of this property. Although obtaining a full characterization for arbitrary $n\in\mathbb{N}$ and $\mathbf{y}\in\mathbb{N}^n$ remains elusive, we do so for $n=2,3$. Given the technicality of these results, we introduce the notion of minimally invariant car lengths, for which the only invariant parking assortment is the all ones preference list. We provide a concise, oracle-based characterization of minimally invariant car lengths for any $n\in\mathbb{N}$. Our results around minimally invariant car lengths also hold for parking sequences

The Glycocalyx and Its Role in Vascular Physiology and Vascular Related Diseases

Purpose—In 2007 the two senior authors wrote a review on the structure and function of the endothelial glycocalyx layer (Weinbaum in Annu Rev Biomed Eng 9:121–167, 2007). Since then there has been an explosion of interest in this hydrated gel-like structure that coats the luminal surface of endothelial cells that line our vasculature due to its important functions in (A) basic vascular physiology and (B) vascular related diseases. This review will highlight the major advances that have occurred since our 2007 paper. Methods—A literature search mainly focusing on the role of the glycocalyx in the two major areas described above was performed using electronic databases. Results—In part (A) of this review, the new formulation of the century old Starling principle, now referred to as the Michel–Weinbaum glycoclayx model or revised Starling hypothesis, is described including new subtleties and physiological ramifications. New insights into mechanotransduction and release of nitric oxide due to fluid shear stress sensed by the glycocalyx are elaborated. Major advances in understanding the organization and function of glycocalyx components, and new techniques for measuring both its thickness and spatio-chemical organization based on super resolution, stochastic optical reconstruction microscopy (STORM) are presented. As discussed in part (B) of this review, it is now recognized that artery wall stiffness associated with hypertension and aging induces glycocalyx degradation, endothelial dysfunction and vascular disease. In addition to atherosclerosis and cardiovascular diseases, the glycocalyx plays an important role in lifestyle related diseases (e.g., diabetes) and cancer. Infectious diseases including sepsis, Dengue, Zika and Corona viruses, and malaria also involve the glycocalyx. Because of increasing recognition of the role of the glycocalyx in a wide range of diseases, there has been a vigorous search for methods to protect the glycocalyx from degradation or to enhance its synthesis in disease environments. Conclusion—As we have seen in this review, many important developments in our basic understanding of GCX structure, function and role in diseases have been described since the 2007 paper. The future is wide open for continued GCX research

Direct current stimulation of endothelial monolayers induces a transient and reversible increase in transport due to the electroosmotic effect

We investigated the effects of direct current stimulation (DCS) on fluid and solute transport across endothelial cell (EC) monolayers in vitro. Our motivation was transcranial direct current stimulation (tDCS) that has been investigated for treatment of neuropsychiatric disorders, to enhance neurorehabilitation, and to change cognition in healthy subjects. The mechanisms underlying this diversity of applications remain under investigation. To address the possible role of blood-brain barrier (BBB) changes during tDCS, we applied direct current to cultured EC monolayers in a specially designed chamber that generated spatially uniform direct current. DCS induced fluid and solute movement across EC layers that persisted only for the duration of the stimulation suggesting an electroosmosis mechanism. The direction of induced transport reversed with DCS polarity – a hallmark of the electroosmotic effect. The magnitude of DCS-induced flow was linearly correlated to the magnitude of the applied current. A mathematical model based on a two-pore description of the endothelial transport barrier and a Helmholtz model of the electrical double layer describes the experimental data accurately and predicts enhanced significance of this mechanism in less permeable monolayers. This study demonstrates that DCS transiently alters the transport function of the BBB suggesting a new adjunct mechanism of tDCS

An Investigative, Cooperative Learning Approach for General Chemistry Laboratories

The integration of research and education is an essential component of our university’s teaching philosophy. Recently, we made a curricular revision to facilitate such an approach in the General Chemistry Laboratory, to teach students that investigative approaches are at the core of sciences. The curriculum revision included new interdisciplinary experiments and a research project. Investigative, peer review, and cooperative learning strategies were introduced to enhance student learning and engagement. An environment in which students can analyze results within a laboratory session and reach comprehensive and quantitative conclusions was encouraged. To assess our results, students completed questionnaires, evaluated their peers and themselves. Instructors evaluated students through written reports, oral presentations, pre- and post test, a practical exam and a final exam. Assessments of the learning outcomes were performed to determine the level of research skills development, the improvement in laboratory techniques, and depth in analysis of concepts. The experimental designs, implementation of results, and comparisons of student performances using traditional approaches are presented

Occludin Independently Regulates Permeability under Hydrostatic Pressure and Cell Division in Retinal Pigment Epithelial Cells

PURPOSE. The aim of this study was to determine the function of the tight junction protein occludin in the control of permeability, under diffusive and hydrostatic pressures, and its contribution to the control of cell division in retinal pigment epithelium. METHODS. Occludin expression was inhibited in the human retinal pigment epithelial cell line ARPE-19 by siRNA. Depletion of occludin was confirmed by Western blot, confocal microscopy, and RT-PCR. Paracellular permeability of cell monolayers to fluorescently labeled 70 kDa dextran, 10 kDa dextran, and 467 Da tetramethylrhodamine (TAMRA) was examined under diffusive conditions or after the application of 10 cm H 2 O transmural pressure. Cell division rates were determined by tritiated thymidine incorporation and Ki67 immunoreactivity. Cell cycle inhibitors were used to determine whether changes in cell division affected permeability. RESULTS. Occludin depletion increased diffusive paracellular permeability to 467 Da TAMRA by 15%, and permeability under hydrostatic pressure was increased 50% compared with control. Conversely, depletion of occludin protein with siRNA did not alter diffusive permeability to 70 kDa and 10 kDa RITCdextran, and permeability to 70 kDa dextran was twofold lower in occludin-depleted cells under hydrostatic pressure conditions. Occludin depletion also increased thymidine incorporation by 90% and Ki67-positive cells by 50%. Finally, cell cycle inhibitors did not alter the effect of occludin siRNA on paracellular permeability. CONCLUSIONS. The data suggest that occludin regulates tight junction permeability in response to changes in hydrostatic pressure. Furthermore, these data suggest that occludin also contributes to the control of cell division, demonstrating a novel function for this tight junction protein. (Invest Ophthalmol Vis Sci

\u3ci\u3eBOA CONSTRICTOR\u3c/i\u3e (Boa Constrictor)

USA: PUERTO RICO: MUNICIPALITY OF CABO ROJO: Cabo Rojo National Wildlife Refuge (17.978958°N, 67.170910oW; NAD 83). 10 November 2014. O. A. Diaz-Marrero. Verified by S. M. Boback. National Museum of Natural History, Smithsonian Institution (USNM Herp Image 2838a, b; photo vouchers). First municipality record for this exotic species; all previous reports were restricted to the Municipality of Mayaguez, located ca. 25 km north of Cabo Rojo National Wildlife Refuge. Reynolds et al. (2013. BioI. Invasions 15:953-959) concluded that Boa Constrictor introductions into Puerto Rico were likely related to the pet trade and that they genetically matched snakes belonging to the South American clade (B. constrictor), instead of B. imperator, the Mesoamerican species (Hynkova et al. 2009. Zool. Sci. 26:623-631). It also represents the first report of this species from a protected area in Puerto Rico

\u3ci\u3eBOA CONSTRICTOR\u3c/i\u3e (Boa Constrictor)

USA: PUERTO RICO: MUNICIPALITY OF CABO ROJO: Cabo Rojo National Wildlife Refuge (17.978958°N, 67.170910oW; NAD 83). 10 November 2014. O. A. Diaz-Marrero. Verified by S. M. Boback. National Museum of Natural History, Smithsonian Institution (USNM Herp Image 2838a, b; photo vouchers). First municipality record for this exotic species; all previous reports were restricted to the Municipality of Mayaguez, located ca. 25 km north of Cabo Rojo National Wildlife Refuge. Reynolds et al. (2013. BioI. Invasions 15:953-959) concluded that Boa Constrictor introductions into Puerto Rico were likely related to the pet trade and that they genetically matched snakes belonging to the South American clade (B. constrictor), instead of B. imperator, the Mesoamerican species (Hynkova et al. 2009. Zool. Sci. 26:623-631). It also represents the first report of this species from a protected area in Puerto Rico