Hormone-induced enhancer assembly requires an optimal level of hormone receptor multivalent interactions

Transcription factors (TFs) activate enhancers to drive cell-specific gene programs in response to signals, but our understanding of enhancer assembly during signaling events is incomplete. Here, we show that androgen receptor (AR) forms condensates through multivalent interactions mediated by its N-terminal intrinsically disordered region (IDR) to orchestrate enhancer assembly in response to androgen signaling. AR IDR can be substituted by IDRs from selective proteins for AR condensation capacity and its function on enhancers. Expansion of the poly(Q) track within AR IDR results in a higher AR condensation propensity as measured by multiple methods, including live-cell single-molecule microscopy. Either weakening or strengthening AR condensation propensity impairs its heterotypic multivalent interactions with other enhancer components and diminishes its transcriptional activity. Our work reveals the requirement of an optimal level of AR condensation in mediating enhancer assembly and suggests that alteration of the fine-tuned multivalent IDR-IDR interactions might underlie AR-related human pathologies.

GPR114/ADGRG5 is activated by its tethered peptide agonist because it is a cleaved adhesion GPCR

Family B2 or adhesion G protein-coupled receptors (AGPCRs) are distinguished by variable extracellular regions that contain a modular protease, termed the GPCR autoproteolysis-inducing domain that self-cleaves the receptor into an N-terminal fragment (NTF) and a C-terminal fragment (CTF), or seven transmembrane domain (7TM). The NTF and CTF remain bound after cleavage through noncovalent interactions. NTF binding to a ligand(s) presented by nearby cells, or the extracellular matrix anchors the NTF, such that cell movement generates force to induce NTF/CTF dissociation and expose the AGPCR tethered peptide agonist. The released tethered agonist (TA) binds rapidly to the 7TM orthosteric site to activate signaling. The orphan AGPCR, GPR114 was reported to be uncleaved, yet paradoxically capable of activation by its TA. GPR114 has an identical cleavage site and TA to efficiently cleave GPR56. Here, we used immunoblotting and biochemical assays to demonstrate that GPR114 is a cleaved receptor, and the self-cleavage is required for GPR114 TA-activation of Gs and no other classes of G proteins. Mutagenesis studies defined features of the GPR114 and GPR56 GAINA subdomains that influenced self-cleavage efficiency. Thrombin treatment of protease-activated receptor 1 leader/AGPCR fusion proteins demonstrated that acute decryption of the GPR114/56 TAs activated signaling. GPR114 was found to be expressed in an eosinophilic-like cancer cell line (EoL-1 cells) and endogenous GPR114 was efficiently self-cleaved. Application of GPR114 TA peptidomimetics to EoL-1 cells stimulated cAMP production. Our findings may aid future delineation of GPR114 function in eosinophil cAMP signaling related to migration, chemotaxis, or degranulation.

Association of Different Biochemical and Hemodynamic Characteristic with Type 2 Diabetes Mellitus and Hypertension in Nephrolithiasis Patients

Background Although Nephrolithiasis is a common condition caused by a wide variety of metabolic or environmental disturbances, its being one of the major factor of morbidity. Incidence of kidney stone disease (KSD) is highly affected by metabolic disorders and change in blood pressure and glucose. Objective To find out association of different biochemical and hemodynamic parameters with various glycemic status and hypertension in kidney stone disease. Method A cross sectional study was conducted in patients diagnosed as nephrolithiasis by using re¬nal ultrasonography and underwent nephrectomy between January 2019 to January 2021 in Shahid Dharmabhakta National Transplant Centre (SDNTC). A total of 100 subjects with 60 male and 40 females were enrolled. Glycemic status was categorized based on criteria of American Diabetes Association (ADA) and hypertension was defined as BP ≥ 140/90 mm Hg in right arm supine position. All biochemical and hemodynamic profile was carried out following standard protocol. Result Out of 100 patients enrolled, pre-diabetes accounted for 31% followed by diabetes (4%). However, hypertension comprised of 66% in total subjects. Serum urea, cholesterol and triglyceride level were found to be increased by 84.6%, 67.7% and 64.7% respectively in diabetes followed by increase of 3.9%, 19.5% and 3.1% respectively in prediabetes when compared to normal glycemic condition in nephrolithiasis subjects. Serum fasting blood glucose, creatinine and uric acid level was observed significantly higher (p=0.003, p=0.004, p < 0.001 respectively) in hypertensive patients. Duration of hospital stay was also seen positively correlated with hypertension. Conclusion Not only diabetes, prediabetes also manifests the increased risk of kidney stone disease along with hypertension. There is significant impairment in renal function and lipid profile based on diabetes mellitus and hypertension. Early identifying these systemic diseases, different biochemical and hemodynamic parameters and proper treatment accordingly may minimize risk and prevent serious complication in these patients.

Understanding the interactive effects of dietary leucine with isoleucine and valine in the modern commercial broiler

A study was conducted to understand the relationship among dietary branched-chain amino acids (BCAA) on the performance of Ross 344 × 708 male broilers. A total of 2,592 d-old male chicks were randomly placed into 144-floor pens according to a 2³ full factorial central composite design (CCD) with 20 treatments (14 treatments and 6 center points). Each treatment consisted of varying digestible Ile:Lys (52 to 75), Val:Lys (64 to 87), and Leu:Lys (110 to 185) ratios. Birds and feed were weighed at 20 and 34 d of age to determine body weight gain (BWG), feed intake, and feed conversion ratio (FCR). At 35 d of age, feather amino acid composition and carcass characteristics were evaluated. Data were analyzed as CCD using the surface response option of JMP v. 15. Body weight gain (1,332 g; P < 0.001; R² = 0.93) and FCR (1.54; P = 0.002; R² = 0.88) were optimized at the lowest Leu:Lys ratio (110) with moderate Val:Lys (78 to 79) and Ile:Lys (65 to 66) ratios. Poorer BWG and FCR were observed as Leu:Lys ratio increased while increasing Val:Lys and Ile:Lys ratios alleviated the poor performance. Carcass (71.5%; P = 0.031; R² = 0.76) and breast yield (26.7%; P < 0.001; R² = 0.96) were maximized at the highest Leu:Lys ratio. This effect was complemented by increasing Ile:Lys ratio beyond 68. Lower Ile:Lys and Val:Lys ratios were required to maximize carcass and breast yield at the lowest Leu:Lys ratio. However, this strategy yielded less meat than providing a high Leu:Lys ratio diet. Dietary BCAA had little effect on altering the composition of feather protein and amino acid (P > 0.10). These results suggest that optimum BCAA ratios to Lys may vary depending on response criteria and demonstrate the importance of maintaining proper Val and Ile ratios centered on dietary Leu. Live performance can be optimized in diets with low Leu:Lys ratios; however, meat yield can be enhanced by increasing dietary Leu:Lys along with Ile:Lys ratios.

Comparative pathology, molecular pathogenicity, immunological features, and genetic characterization of three highly pathogenic human coronaviruses (MERS-CoV, SARS-CoV, and SARS-CoV-2)

The last two decades have witnessed the emergence of three deadly coronaviruses (CoVs) in humans: severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome coronavirus (MERS-CoV), and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). There are still no reliable and efficient therapeutics to manage the devastating consequences of these CoVs. Of these, SARS-CoV-2, the cause of the currently ongoing coronavirus disease 2019 (COVID-19) pandemic, has posed great global health concerns. The COVID-19 pandemic has resulted in an unprecedented crisis with devastating socio-economic and health impacts worldwide. This highlights the fact that CoVs continue to evolve and have the genetic flexibility to become highly pathogenic in humans and other mammals. SARS-CoV-2 carries a high genetic homology to the previously identified CoV (SARS-CoV), and the immunological and pathogenic characteristics of SARS-CoV-2, SARS-CoV, and MERS contain key similarities and differences that can guide therapy and management. This review presents salient and updated information on comparative pathology, molecular pathogenicity, immunological features, and genetic characterization of SARS-CoV, MERS-CoV, and SARS-CoV-2; this can help in the design of more effective vaccines and therapeutics for countering these pathogenic CoVs.

Efficient Bayesian inference of fully stochastic epidemiological models with applications to COVID-19

Epidemiological forecasts are beset by uncertainties about the underlying epidemiological processes, and the surveillance process through which data are acquired. We present a Bayesian inference methodology that quantifies these uncertainties, for epidemics that are modelled by (possibly) non-stationary, continuous-time, Markov population processes. The efficiency of the method derives from a functional central limit theorem approximation of the likelihood, valid for large populations. We demonstrate the methodology by analysing the early stages of the COVID-19 pandemic in the UK, based on age-structured data for the number of deaths. This includes maximum a posteriori estimates, Markov chain Monte Carlo sampling of the posterior, computation of the model evidence, and the determination of parameter sensitivities via the Fisher information matrix. Our methodology is implemented in PyRoss, an open-source platform for analysis of epidemiological compartment models.

Low temperature and high magnetic field performance of a commercial piezo-actuator probed via laser interferometry

The advances in the fields of scanning probe microscopy, scanning tunneling spectroscopy, point contact spectroscopy, and point contact Andreev reflection spectroscopy to study the properties of conventional and quantum materials under cryogenic conditions have prompted the development of nanopositioners and nanoscanners with enhanced spatial resolution. Piezoelectric-actuator stacks as nanopositioners with working strokes of 10 μm and positioning resolution ∼(1-10) nm are desirable for both basic research and industrial applications. However, information on the performance of most commercial piezoelectric actuators in cryogenic environment and in the presence of magnetic fields in excess of 5 T is generally not available. In particular, the magnitude, the rate, and the associated hysteresis of the piezo-displacement at cryogenic temperatures are the most relevant parameters that determine whether a particular piezoelectric actuator can be used as a nanopositioner. Here, the design and realization of an experimental setup based on interferometric techniques to characterize a commercial piezoelectric actuator over a temperature range of 2 K ≤ T ≤ 260 K and magnetic fields up to 6 T are presented. The studied piezoelectric actuator has a maximum displacement of 30 μm at room temperature for a maximum driving voltage of 75 V, which reduces to 1.2 μm with an absolute hysteresis of 9.1±3.3nm at T = 2 K. The magnetic field is shown to have no substantial effect on the piezo-properties of the studied piezoelectric-actuator stack.

Controlled Optofluidic Crystallization of Colloids Tethered at Interfaces

We report experiments that show rapid crystallization of colloids tethered to an oil-water interface in response to laser illumination. This light-induced transition is due to a combination of long-ranged thermophoretic pumping and local optical binding. We show that the flow-induced force on the colloids can be described as the gradient of a potential. The nonequilibrium steady state due to local heating thus admits an effective equilibrium description. The optofluidic manipulation explored in this work opens novel ways to manipulate and assemble colloidal particles.

Mechanisms of adhesion G protein-coupled receptor activation

Adhesion G protein-coupled receptors (AGPCRs) are a thirty-three-member subfamily of Class B GPCRs that control a wide array of physiological processes and are implicated in disease. AGPCRs uniquely contain large, self-proteolyzing extracellular regions that range from hundreds to thousands of residues in length. AGPCR autoproteolysis occurs within the extracellular GPCR autoproteolysis-inducing (GAIN) domain that is proximal to the N terminus of the G protein-coupling seven-transmembrane-spanning bundle. GAIN domain-mediated self-cleavage is constitutive and produces two-fragment holoreceptors that remain bound at the cell surface. It has been of recent interest to understand how AGPCRs are activated in relation to their two-fragment topologies. Dissociation of the AGPCR fragments stimulates G protein signaling through the action of the tethered-peptide agonist stalk that is occluded within the GAIN domain in the holoreceptor form. AGPCRs can also signal independently of fragment dissociation, and a few receptors possess GAIN domains incapable of self-proteolysis. This has resulted in complex theories as to how these receptors are activated in vivo, complicating pharmacological advances. Currently, there is no existing structure of an activated AGPCR to support any of the theories. Further confounding AGPCR research is that many of the receptors remain orphans and lack identified activating ligands. In this review, we provide a detailed layout of the current theorized modes of AGPCR activation with discussion of potential parallels to mechanisms used by other GPCR classes. We provide a classification means for the ligands that have been identified and discuss how these ligands may activate AGPCRs in physiological contexts.

Acetylation of Aβ42 at Lysine 16 Disrupts Amyloid Formation

The residue lysine 28 (K28) is known to form an important salt bridge that stabilizes the Aβ amyloid structure, and acetylation of lysine 28 (K28Ac) slows the Aβ42 fibrillization rate but does not affect fibril morphology. On the other hand, acetylation of lysine 16 (K16Ac) residue greatly diminishes the fibrillization property of Aβ42 peptide and also affects its toxicity. This is due to the fact that lysine 16 acetylated amyloid beta peptide forms amorphous aggregates instead of amyloid fibrils. This is likely a result of increased hydrophobicity of the K16-A21 region due to K16 acetylation, as confirmed by molecular dynamic simulation studies. The calculated results show that the hydrophobic patches of aggregates from acetylated peptides were different when compared to wild-type (WT) peptide. K16Ac and double acetylated (KKAc) peptide aggregates show significantly higher cytotoxicity compared to the WT or K28Ac peptide aggregates alone. However, the heterogeneous mixture of WT and acetylated Aβ42 peptide aggregates exhibited higher free radical formation as well as cytotoxicity, suggesting dynamic interactions between different species could be a critical contributor to Aβ pathology.

Adherence to Iron, Folic Acid and Calcium Supplement and Factors Affecting it among the Antenatal Care Attending Women in a Tertiary Care Hospital: A Cross Sectional Study

Background Pregnancy or gestation is the time during which a single or more children grows and develops inside a woman. Antenatal care improves the pregnancy outcomes under which a group of medication i.e. iron, folic acid and calcium are supplemented. Despite the effectiveness of such supplements, poor clinical outcomes are often encountered because of poor-adherence to the regimen. Objective To determine the adherence pattern and factors affecting adherence in antenatal care patients under iron, folic acid, and calcium therapy. Method A cross-sectional study was conducted in Dhulikhel Hospital, Kathmandu University Hospital. Pregnant women attending antenatal care under iron, folic acid, and calcium therapy fulfilling the inclusion criteria were enrolled in this study. After obtaining the informed consent from the patients, structured questionnaire was used to interview the patients. Statistical analysis was performed by using SPSS 23.0. P-value < 0.05 was considered as statistically significant. Result Among 191 patients enrolled in this study majority (39.3%) of them belonged to age group 26-30 years. More than half (61.3%) of the patients were illiterate. Of the total 191, 64.40% were non-adherent to the medication. Forgetfulness was the main reason for missing the dose in majority (52.06%) of the non-adherent subjects while adverse effects (55.40%) was the most prominent cause for discontinuing the medication among non-adherent participants. Significant association was found between patients' adherence and busy work schedule, visiting doctor for follow up. Conclusion More than half of the patients had not adhered to the medication under antenatal care. Forgetfulness was the most common factor for missing the dose in nonadherent patients. Illiteracy was associated with poor adherence. Patient-provider relationship, Socio-economic factors were determined as major barrier to medication adherence.

Periodic Orbits of Active Particles Induced by Hydrodynamic Monopoles

Terrestrial experiments on active particles, such as Volvox, involve gravitational forces, torques and accompanying monopolar fluid flows. Taking these into account, we analyze the dynamics of a pair of self-propelling, self-spinning active particles between widely separated parallel planes. Neglecting flow reflected by the planes, the dynamics of orientation and horizontal separation is symplectic, with a Hamiltonian exactly determining limit cycle oscillations. Near the bottom plane, gravitational torque damps and reflected flow excites this oscillator, sustaining a second limit cycle that can be perturbatively related to the first. Our work provides a theory for dancing Volvox and highlights the importance of monopolar flow in active matter.

Effects of additional dosage of vitamin D3, vitamin D2, and 25-hydroxyvitamin D3 on calcium and phosphorus utilization, egg quality and bone mineralization in laying hens

Vitamin D is essential for the metabolism of calcium (Ca) and phosphorus (P) in birds. The objective of the study was to evaluate the effect of different isoforms of dietary vitamin D on Ca and P utilization, egg quality, and bone mineralization of laying hens. A total of 42 Lohmann white laying hens at 57 wk of age were randomly assigned to 7 dietary treatments for 6 wk. Dietary treatments were: 3,000 IU/kg Vit D₃ as control, and control with additional 3,000 IU/kg 25-hydroxyvitamin D₃ (T1), 9,000 IU/kg 25-hydroxyvitamin D₃ (T2), 3,000 IU/kg vitamin D3 (T3), 9,000 IU/kg vitamin D₃ (T4), 3,000 IU/kg of vitamin D₂ (T5), or 9,000 IU/kg of vitamin D₂ (T6). Egg production and egg quality were measured weekly. Fecal samples were collected at weeks 2 and 6 to measure Ca and P utilization. After 6 wk, the left tibia and femurs were collected to measure bone mineral density (BMD) and bone mineral content (BMC). A 1-way ANOVA with Tukey HSD means separation test was used for statistical analysis. There were no significant differences in egg production, egg quality, BMD, or BMC of tibia and femurs among the treatments (P > 0.05). T6 significantly reduced feed intake (P < 0.05). The apparent total tract digestibility (ATTD) of Ca was higher (P < 0.012) in treatments supplemented with additional vitamin D, irrespective of forms. The ATTD of P was higher (P < 0.0001) in T5 compared to the other treatments at both time points. The utilization of Ca and P by laying hens can be improved through the addition of different isoforms of vitamin D in diets. However, additional vitamin D supplementation to laying hens, regardless of forms, had no effect on either bone mineralization or measures of egg quality.

Fluorescent probes with high pKa values based on traditional, near-infrared rhodamine, and hemicyanine fluorophores for sensitive detection of lysosomal pH variations

Sterically hindered fluorescent probes (A-C) have been developed by introducing 2-aminophenylboronic acid pinacol ester to a traditional, A, a near-infrared rhodamine dye, B, and a near-infrared hemicyanine dye, C, forming closed spirolactam ring structures. Probe A was non-fluorescent under basic pH conditions whereas probes B and C were moderately fluorescent with fluorescence quantum yields of 9% and 5% in pH 7.4 PBS buffer containing 1% ethanol, respectively. With all probes increasing acidity leads to significant increases in fluorescence at 580 nm, 644 and 744 nm for probes A, B and C with fluorescence quantum yields of 26%, 21% and 10% in pH 4.5 PBS buffer containing 1% ethanol, respectively. Probes A, B and C were calculated to have pKa values of 5.81, 5.45 and 6.97. The difference in fluorescence under basic conditions is ascribed to easier opening of the closed spirolactam ring configurations due to significant steric hindrance between the 2-aminophenylboronic acid pinacol ester residue and an adjacent H atom in the xanthene derivative moiety in probe B or C. The probes show fast, reversible, selective and sensitive fluorescence responses to pH changes, and are capable of sensing lysosomal pH variations in living cells.

Impact of a multicarbohydrase containing α-galactosidase and xylanase on ileal digestible energy, crude protein digestibility, and ileal amino acid digestibility in broiler chickens

Exogenous enzymatic supplementation of poultry feeds, including α-galactosidase and xylanase, has been shown to increase metabolically available energy, although little information has been published on the impact on amino acid digestibility. An experiment was conducted to investigate a multicarbohydrase containing α-galactosidase and xylanase on amino acid digestibility, ileal digestible energy (IDE), and CP in male broiler chicks. The experiment was a 2 × 2 (diet × enzyme) factorial arrangement with 15 replicates of 8 male broilers per replicate raised for 21 d in a battery setting. The 2 dietary treatments included a positive control (PC) and a negative control (NC) diet formulated to contain 2.5% less calculated AME and digestible amino acids. Each of these diets was fed with and without enzyme. Broilers were fed a starter diet from 0-14 d (crumble) and a grower from 14-21 d (pellet). Birds were sampled on day 21 to determine ileal amino acid digestibility, IDE, and CP digestibility. Titanium dioxide (TiO2) was used as an indigestible marker for the determination of digestibility coefficients. Total ileal amino acid digestibility was increased (P = 0.008) by 3.80% with the inclusion of enzyme. Methionine and lysine digestibility was improved (P < 0.05) with the inclusion of enzyme by 3.37% and 2.61%, respectively. Enzyme inclusion increased (P = 0.001) cysteine digestibility by 9.3%. Diet-influenced ileal amino acid digestibility with tryptophan, threonine, isoleucine, and valine digestibility being increased (P < 0.05) in the PC when compared to the NC. IDE was decreased (P = 0.037) in broilers fed the NC diet by 100 kcal/kg feed when compared to broilers fed the PC diet. Enzyme inclusion increased (P = 0.047) IDE value by 90 kcal/kg. Crude protein digestibility was not influenced by diet; however, similar improvements in CP digestibility with enzyme inclusion were observed as with energy. These data support the benefits of a multicarbohydrase containing α-galactosidase and xylanase inclusion to improve nutrient and ileal amino acid digestibility across multiple dietary nutrient profiles.

New Near-infrared Fluorescent Probes with Single-photon Anti-Stokes-shift Fluorescence for Sensitive Determination of pH Variances in Lysosomes with a Double-Checked Capability

Two near-infrared luminescent probes with Stokes-shift and single-photon anti-Stokes-shift fluorescence properties for sensitive determination of pH variance in lysosomes have been synthesized. A morpholine residue in probe A which serves as a targeting group for lysosomes in viable cells was attached to the fluorophores via a spirolactam moiety while a mannose residue was ligated to probe B resulting in increased biocompatibility and solubility in water. Probes A and B contain closed spirolactam moieties, and show no Stokes-shift or anti-Stokes-shift fluorescence under neutral or alkali conditions. However, the probes incrementally react to pH variance from 7.22 to 2.76 with measurable increases in both Stokes-shift and anti-Stokes-shift fluorescence at 699 nm and 693 nm under 645 nm and 800 nm excitation, respectively. This acid-activated fluorescence is produced by the breaking of the probe spirolactam moiety, which greatly increased overall π-conjugation in the probes. These probes possess upconversion near-infrared fluorescence imaging advantages including minimum cellular photo-damage, tissue penetration, and minimum biological fluorescence background. They display excellent photostability with low dye photobleaching and show good biocompatibility. They are selective and capable of detecting pH variances in lysosomes at excitation with two different wavelengths, i.e., 645 and 800 nm.

Fast Bayesian inference of the multivariate Ornstein-Uhlenbeck process

The multivariate Ornstein-Uhlenbeck process is used in many branches of science and engineering to describe the regression of a system to its stationary mean. Here we present an O(N) Bayesian method to estimate the drift and diffusion matrices of the process from N discrete observations of a sample path. We use exact likelihoods, expressed in terms of four sufficient statistic matrices, to derive explicit maximum a posteriori parameter estimates and their standard errors. We apply the method to the Brownian harmonic oscillator, a bivariate Ornstein-Uhlenbeck process, to jointly estimate its mass, damping, and stiffness and to provide Bayesian estimates of the correlation functions and power spectral densities. We present a Bayesian model comparison procedure, embodying Ockham's razor, to guide a data-driven choice between the Kramers and Smoluchowski limits of the oscillator. These provide novel methods of analyzing the inertial motion of colloidal particles in optical traps.

Redox Reaction Triggered Nanomotors Based on Soft-Oxometalates With High and Sustained Motility

The recent interest in self-propulsion raises an immediate challenge in facile and single-step synthesis of active particles. Here, we address this challenge and synthesize soft oxometalate nanomotors that translate ballistically in water using the energy released in a redox reaction of hydrazine fuel with the soft-oxometalates. Our motors reach a maximum speed of 370 body lengths per second and remain motile over a period of approximately 3 days. We report measurements of the speed of a single motor as a function of the concentration of hydrazine. It is also possible to induce a transition from single-particle translation to collective motility with biomimetic bands simply by tuning the loading of the fuel. We rationalize the results from a physicochemical hydrodynamic theory. Our nanomotors may also be used for transport of catalytic materials in harsh chemical environments that would otherwise passivate the active catalyst.

Influence of Mn co-doping on the magnetic properties of planar arrays of GaxFe4−xN nanocrystals in a GaN matrix

Mn co-doping affects the formation of iron nitride nanocrystals in a GaN matrix, determining the system's structural and magnetic properties.

Fluorescent Probes for Sensitive and Selective Detection of pH Changes in Live Cells in Visible and Near-infrared Channels

We report five fluorescent probes based on coumarin-hybridized fluorescent dyes with spirolactam ring structures (A-E) to detect pH changes in live cell by monitoring visible and near-infrared fluorescence changes. Under physiological or basic conditions, the fluorescent probes A, B, C, D and E preserve their spirolactam ring-closed forms and only display fluorescent peaks in the visible region corresponding to coumarin moieties at 497, 483, 498, 497 and 482 nm, respectively. However, at acidic pH, the rings of the spirolactam forms of the fluorescent probes A, B, C, D and E open up, generating new near-infrared fluorescence peaks at 711, 696, 707, 715, and 697 nm, respectively, through significantly extended π-conjugation to coumarin moieties of the fluorophores. The fluorescent probes B and E can be applied to visualize pH changes by monitoring visible as well as near-infrared fluorescence changes. This helps avoid fluorescence imaging blind spots at neutral or basic pH, which typical pH fluorescent probes encounter. The probes exhibit high sensitivity to pH changes, excellent photostability, low auto-fluorescence background and good cell membrane permeability.

Direct verification of the fluctuation-dissipation relation in viscously coupled oscillators

The fluctuation-dissipation relation, a central result in nonequilibrium statistical physics, relates equilibrium fluctuations in a system to its linear response to external forces. Here we provide a direct experimental verification of this relation for viscously coupled oscillators, as realized by a pair of optically trapped colloidal particles. A theoretical analysis, in which interactions mediated by slow viscous flow are represented by nonlocal friction tensors, matches experimental results and reveals a frequency maximum in the amplitude of the mutual response which is a sensitive function of the trap stiffnesses and the friction tensors. This allows for its location and width to be tuned and suggests the utility of the trap setup for accurate two-point microrheology.

Colloidal transport by active filaments

Enhanced colloidal transport beyond the limit imposed by diffusion is usually achieved through external fields. Here, we demonstrate the ballistic transport of a colloidal sphere using internal sources of energy provided by an attached active filament. The latter is modeled as a chain of chemo-mechanically active beads connected by potentials that enforce semi-flexibility and self-avoidance. The fluid flow produced by the active beads and the forces they mediate are explicitly taken into account in the overdamped equations of motion describing the colloid-filament assembly. The speed and efficiency of transport depend on the dynamical conformational states of the filament. We characterize these states using filament writhe as an order parameter and identify ones yielding maxima in speed and efficiency of transport. The transport mechanism reported here has a remarkable resemblance to the flagellar propulsion of microorganisms which suggests its utility in biomimetic systems.

Fast Bayesian inference of optical trap stiffness and particle diffusion

Bayesian inference provides a principled way of estimating the parameters of a stochastic process that is observed discretely in time. The overdamped Brownian motion of a particle confined in an optical trap is generally modelled by the Ornstein-Uhlenbeck process and can be observed directly in experiment. Here we present Bayesian methods for inferring the parameters of this process, the trap stiffness and the particle diffusion coefficient, that use exact likelihoods and sufficient statistics to arrive at simple expressions for the maximum a posteriori estimates. This obviates the need for Monte Carlo sampling and yields methods that are both fast and accurate. We apply these to experimental data and demonstrate their advantage over commonly used non-Bayesian fitting methods.

Near-Infrared Fluorescent Probes with Large Stokes Shifts for Sensing Zn(II) Ions in Living Cells

We report two new near-infrared fluorescent probes based on Rhodol counterpart fluorophore platforms functionalized with dipicolylamine Zn(II)-binding groups. The combinations of the pendant amines and fluorophores provide the probes with an effective three-nitrogen-atom and one-oxygen-atom binding motif. The fluorescent probes with large Stokes shifts offer sensitive and selective florescent responses to Zn(II) ions over other metal ions, allowing a reversible monitoring of Zn(II) concentration changes in living cells, and detecting intracellular Zn(II) ions released from intracellular metalloproteins.

Universal Hydrodynamic Mechanisms for Crystallization in Active Colloidal Suspensions

The lack of detailed balance in active colloidal suspensions allows dissipation to determine stationary states. Here we show that slow viscous flow produced by polar or apolar active colloids near plane walls mediates attractive hydrodynamic forces that drive crystallization. Hydrodynamically mediated torques tend to destabilize the crystal but stability can be regained through critical amounts of bottom heaviness or chiral activity. Numerical simulations show that crystallization is not nucleational, as in equilibrium, but is preceded by a spinodal-like instability. Harmonic excitations of the active crystal relax diffusively but the normal modes are distinct from an equilibrium colloidal crystal. The hydrodynamic mechanisms presented here are universal and rationalize recent experiments on the crystallization of active colloids.

Flow-induced nonequilibrium self-assembly in suspensions of stiff, apolar, active filaments

Active bodies in viscous fluids interact hydrodynamically through self-generated flows. A stiff, apolar, active filament generates symmetric fluid flow around it and thus cannot self-propel. Here we study the mobility and aggregation induced by hydrodynamic flow in a suspension of stiff, apolar, active filaments. We consider two types of active filaments, with those producing extensile or contractile flows along their long axis. Lateral hydrodynamic attractions in extensile filaments lead, independent of the volume fraction, to anisotropic aggregates which translate and rotate ballistically. Lateral hydrodynamic repulsions in contractile filaments lead to microstructured states, where the degree of clustering increases with the volume fraction and the filament motion is always diffusive. Our results demonstrate that the interplay between active hydrodynamic flows and anisotropic excluded volume interactions provides a generic nonequilibrium mechanism for hierarchical self-assembly of active soft matter.

Brownian microhydrodynamics of active filaments

Slender bodies capable of spontaneous motion in the absence of external actuation in an otherwise quiescent fluid are common in biological, physical and technological contexts. The interplay between the spontaneous fluid flow, Brownian motion, and the elasticity of the body presents a challenging fluid-structure interaction problem. Here, we model this problem by approximating the slender body as an elastic filament that can impose non-equilibrium velocities or stresses at the fluid-structure interface. We derive equations of motion for such an active filament by enforcing momentum conservation in the fluid-structure interaction and assuming slow viscous flow in the fluid. The fluid-structure interaction is obtained, to any desired degree of accuracy, through the solution of an integral equation. A simplified form of the equations of motion, which allows for efficient numerical solutions, is obtained by applying the Kirkwood-Riseman superposition approximation to the integral equation. We use this form of equation of motion to study dynamical steady states in free and hinged minimally active filaments. Our model provides the foundation to study collective phenomena in momentum-conserving, Brownian, active filament suspensions.

Acute Disseminated Encephalomyelitis Following Typhoid Fever: A Case Report

The involvement of central nervous system in children with typhoid fever is common. Acute disseminated encephalomyelitis is a rare immune mediated and demyelinating disease of the central nervous system that usually affects children. We report a 7-year-old child with typhoid fever who developed acute cerebellar syndrome due to acute disseminated encephalomyelitis.Journal of College of Medical Sciences-Nepal, 2013, Vol-9, No-4, 55-58 DOI: http://dx.doi.org/10.3126/jcmsn.v9i4.10237

Irreducible representations of oscillatory and swirling flows in active soft matter

Recent experiments imaging fluid flow around swimming microorganisms have revealed complex time-dependent velocity fields that differ qualitatively from the stresslet flow commonly employed in theoretical descriptions of active matter. Here we obtain the most general flow around a finite sized active particle by expanding the surface stress in irreducible Cartesian tensors. This expansion, whose first term is the stresslet, must include, respectively, third-rank polar and axial tensors to minimally capture crucial features of the active oscillatory flow around translating Chlamydomonas and the active swirling flow around rotating Volvox. The representation provides explicit expressions for the irreducible symmetric, antisymmetric, and isotropic parts of the continuum active stress. Antisymmetric active stresses do not conserve orbital angular momentum and our work thus shows that spin angular momentum is necessary to restore angular momentum conservation in continuum hydrodynamic descriptions of active soft matter.

Evaluation of anti-secretory and anti-ulcerogenic activities of avipattikar churna on the peptic ulcers in experimental rats

BACKGROUND

Avipattikar churna, a poly-herbal formulation, is one of the popular ayurvedic formulations which is used for peptic ulcer diseases but the scientific documentation with regards to its effect for the indication is lacking.

AIMS

This study was carried out to evaluate the anti-secretory and the anti-ulcerogenic activities of the churna and to compare its activity with that of ranitidine in a pyloric ligated model of rats.

MATERIAL AND METHODS

Four groups of rats with 6 animals in each served as the ulcer controls, churna low dose (500 mg/kg), churna high dose (750mg/kg) and ranitidine (25mg/kg). The control group rats received only vehicle (2% (v/v) gum acacia), while the rats of the other groups received the respective dose of the churna or ranitidine which was suspended in the vehicle. The treatments were given twice a day, orally, for two days. After 1 hour of the last dose, pyloric ligations were performed and the rats were sacrificed for evaluation after four hours of the ligations. The gastric contents were collected and its volume, pH and acidity were measured. The numbers of ulcers and their lengths were measured which were used to calculate the gastric irritancy index and the curative ratio. The histological examinations of the gastric tissues were also performed.

RESULTS

The churna, in both doses, significantly decreased the volumes of the gastric contents, the ulcer score, the length of the ulcer, the gastric irritancy index and pH increased as compared to those in the control group. The effects of the churna were comparable to that of ranitidine. The histopathological evaluation of the gastric tissue also supported the results.

CONCLUSION

Avipattikar churna has anti-secretory and anti-ulcerogenic effects which are comparable to those of ranitidine in peptic ulcer diseases.

Physicochemical and functional characteristics of lentil starch

The physicochemical properties of lentil starch were measured and linked up with its functional properties and compared with those of corn and potato starches. The amylose content of lentil starch was the highest among these starches. The crystallinity and gelatinization enthalpy of lentil starch were the lowest among these starches. The high amylose: amylopectin ratio in lentil starch resulted into low crystallinity and gelatinization enthalpy. Gelatinization and pasting temperatures of lentil starch were in between those of corn and potato starches. Lentil starch gels showed the highest storage modulus, gel strength and pasting viscosity than corn and potato starch gels. Peleg's model was able to predict the stress relaxation data of these starches well (R(2)>0.98). The elastic modulus of lentil starch gel was less frequency dependent and higher in magnitude at high temperature (60 °C) than at lower temperature (10 °C). Lentil starch is suitable where higher gel strengthened pasting viscosity are desired.

Autonomous motility of active filaments due to spontaneous flow-symmetry breaking

We simulate the nonlocal Stokesian hydrodynamics of an elastic filament which is active due a permanent distribution of stresslets along its contour. A bending instability of an initially straight filament spontaneously breaks flow symmetry and leads to autonomous filament motion which, depending on conformational symmetry, can be translational or rotational. At high ratios of activity to elasticity, the linear instability develops into nonlinear fluctuating states with large amplitude deformations. The dynamics of these states can be qualitatively understood as a superposition of translational and rotational motion associated with filament conformational modes of opposite symmetry. Our results can be tested in molecular-motor filament mixtures, synthetic chains of autocatalytic particles, or other linearly connected systems where chemical energy is converted to mechanical energy in a fluid environment.

Rectal Misoprostol versus Intramuscular Oxytocin for Prevention of Post Partum Hemorrhage

Background Postpartum hemorrhage (PPH) is an important cause of maternal morbidity and mortality especially in the developing countries. Compared to expectant management, active management decreases the incidence of PPH. Objective To compare the effectiveness of rectal misoprostol with intramuscular oxytocin in the prevention of postpartum hemorrhage. Methods This is a prospective, randomized and analytical study from 1stSeptember 2009 to 28th February 2010 at Department of Obstetrics and Gynecology, Dhulkhel Hospital - Kathmandu University Hospital, Dhulikhel, Nepal. A total of 200 women were included to receive either 1000 micrograms rectal misoprostol tablets or 10 units of oxytocin intramuscularly. Primary outcome measures were the incidence of postpartum hemorrhage or a change in hematocrit or hemoglobin from admission to day two post delivery. Secondary outcome measures including severe postpartum hemorrhage and the duration of the third stage of labor were noted. Also the side effects of both misoprostol and oxytocin were recorded. Results The frequency of postpartum hemorrhage was 4% in the misoprostol subjects and 6% in the control subjects (P=0.886) There were no significant difference among the groups in the drop of hematocrit (P>0.05). Secondary outcome measures including severe postpartum hemorrhage and the duration of the third stage of labor were similar in both groups. Similarly, the side effects between the misoprostol and oxytocin group within 6 hours was statistically significant (p=0.003) whereas the side effects within 24hours was statistically not significant (p=0.106). ConclusionRectal misoprostol is as effective as intravenous oxytocin in preventing postpartum hemorrhage with the similar incidence of side effects and is worthwhile to be used as a uterotonic agent for the routine management of third stage of labor.http://dx.doi.org/10.3126/kumj.v9i1.6254 Kathmandu Univ Med J 2011;9(1):8-12