Viscous Agents Research Articles

Sustained Release Formulation of Hydroxypropyl-β-cyclodextrin Eye Drops Using Xanthan Gum.

Bietti's crystalline dystrophy (BCD) is an autosomal recessive chorioretinal degeneration caused by mutations in the CYP4V2 gene. It is characterized by cholesterol accumulation and crystal-like deposits in the retinas. Hydroxypropyl-β-cyclodextrin (HP-β-CyD) exerts therapeutic effects against BCD by reducing lysosomal dysfunction and inhibiting cytotoxicity in induced pluripotent stem cell (iPSC)-RPE cells established from patient-derived iPS cells. However, the ocular retention of HP-β-CyD is low and needs to be improved. Therefore, this study used a viscous agent to develop a sustained-release ophthalmic formulation containing HP-β-CyD. Our results suggest that HP-β-CyD-containing xanthan gum has a considerably higher sustained release capacity than other viscous agents, such as methylcellulose and sodium alginate. In addition, the HP-β-CyD-containing xanthan gum exhibited pseudoplastic behavior. It was less cytotoxic to human retinal pigment epithelial cells compared with HP-β-CyD alone. Furthermore, the slow release of HP-β-CyD from xanthan gum caused a sustained decrease in free intracellular cholesterol. These results suggest that xanthan gum is a useful substrate for the sustained release formulation of HP-β-CyD, and that HP-β-CyD-containing xanthan gum has potential as an eye drop for BCD treatment.

Evolution of endoscopic mucosal resection (EMR) technique and the reduced recurrence of large colonic polyps from 2012 to 2020

Background Endoscopic mucosal resection (EMR) is an effective method for removing non-pedunculated polyps ≥ 20 mm. We aimed to examine changes in EMR techniques over a 9-year period and evaluate frequency of histologic-confirmed recurrence. Methods We identified patients who underwent EMR of non-pedunculated polyps ≥ 20 mm at a safety net and the Veteran’s Affairs (VA) hospital in Houston, Texas between 2012 and 2020. Odds ratios (ORs) and 95% confidence intervals (CI) for associations with recurrence risk were estimated using multivariable logistic regression. Results 461 unique patients were included. The histologic-confirmed recurrence was 29.0% at 15.6 months median follow up (IQR 12.3 − 17.4). Polyps removed between 2018 and 2020 had a 0.43 decreased odds of recurrence vs. polyps removed between 2012 and 2014. The use of viscous lifting agents increased over time (from 0 to 54%), and the use of saline was associated with increased risk of recurrence (OR 2.28 [CI 1.33 − 3.31]). Conclusions Histologic-confirmed recurrence after EMR for non-pedunculated polyps ≥ 20 mm decreased over the seven year-period. Saline was associated with a higher risk of recurrence and the use of more viscous agents increased over time.

Physical properties of the cytoplasm modulate the rates of microtubule polymerization and depolymerization.

The cytoplasm is a crowded, visco-elastic environment whose physical properties change according to physiological or developmental states. How the physical properties of the cytoplasm impact cellular functions invivo remains poorly understood. Here, we probe the effects of cytoplasmic concentration on microtubules by applying osmotic shifts to fission yeast, moss, and mammalian cells. We show that the rates of both microtubule polymerization and depolymerization scale linearly and inversely with cytoplasmic concentration; an increase in cytoplasmic concentration decreases the rates of microtubule polymerization and depolymerization proportionally, whereas a decrease in cytoplasmic concentration leads to the opposite. Numerous lines of evidence indicate that these effects are due to changes in cytoplasmic viscosity rather than cellular stress responses or macromolecular crowding per se. We reconstituted these effects on microtubules invitro by tuning viscosity. Our findings indicate that, even in normal conditions, the viscosity of the cytoplasm modulates the reactions that underlie microtubule dynamic behaviors.

Effect of viscosity on efficiency of enzyme catalysis of bacterial luciferase coupled with lactate dehydrogenase and NAD(P)H:FMN-Oxidoreductase

One of the current trends of the modern biology figures out cellular enzyme behaviour. Numerous researches look more closely at the chemical composition of creating in vivo simulated media conditions. The aim of this work was to find out a thermodynamic cooperativity of enzymes in a triple-enzyme chain (lactate dehydrogenase + NAD(P)H: FMN-oxidoreductase + bacterial luciferase) under in vivo simulated condition. The thermodynamic cooperativity effects were found out based on the influence of the viscogens (glycerol and sucrose) on the thermal stability of the triple-enzyme system. The results showed that the viscogens do not lead to an increase in the thermal stability of the triple-enzyme system. In addition, organic solvents (sucrose and glycerol) added as viscous agents to the reaction medium altered the kinetics of this triple-enzyme chain, including changing the light emission decay constant (kdec) and quantum yield of luminescence (Q). Plus, sucrose was found to be more efficient in limiting the flexibility of enzymes than glycerol. The high sensitivity of the triple-enzyme system to the viscogens may be connected with a fact that lactate dehydrogenase does not bound with couple enzyme system NAD(P)H: FMN-oxidoreductase + bacterial luciferase inside the real cell. Since this approach may be used as a method to understand the real connection between enzymes in cellular multi-enzyme metabolic chains inside the luminous bacteria cell.

A Study on Closed-Cell Aluminum Foam about Viscosity of Different Viscous Agents

This study compared the effects of viscosity and microscopic mechanism between different viscous agents. Based on macro-analysis and micro-analysis, the comparison were studied, and built the models to explain the results. The different viscous agents and proportion could change the situation around the bubbles and grain size differently. The study gave a new way to analyze the viscosity, further, these factors play an important in effects of viscosity.

Reversing the direction of galvanotaxis with controlled increases in boundary layer viscosity

Weak external electric fields (EFs) polarize cellular structure and direct most migrating cells (galvanotaxis) toward the cathode, making it a useful tool during tissue engineering and for healing epidermal wounds. However, the biophysical mechanisms for sensing weak EFs remain elusive. We have reinvestigated the mechanism of cathode-directed water flow (electro-osmosis) in the boundary layer of cells, by reducing it with neutral, viscous polymers. We report that increasing viscosity with low molecular weight polymers decreases cathodal migration and promotes anodal migration in a concentration dependent manner. In contrast, increased viscosity with high molecular weight polymers does not affect directionality. We explain the contradictory results in terms of porosity and hydraulic permeability between the polymers rather than in terms of bulk viscosity. These results provide the first evidence for controlled reversal of galvanotaxis using viscous agents and position the field closer to identifying the putative electric field receptor, a fundamental, outside-in signaling receptor that controls cellular polarity for different cell types.

Influence of Physical Effects on the Swarming Motility of Pseudomonas aeruginosa

Many species of bacteria can spread over a moist surface via a particular form of collective motion known as “surface swarming”. This form of motility is typically studied by inoculating bacteria on a gel formed by 0.4–1.5% agar, which contains essential nutrients for their growth and proliferation. Using Pseudomonas aeruginosa and its pili-less mutant, ΔPilA, we investigate physical factors that either facilitate or restrict the swarming motility, measured by the rate of increase in area covered by a spreading bacterial colony, i.e., a swarm. The wild-type colony spreads over the agar surface in highly branched structures. The pili-less mutant fills up the area more fully as it spreads, but it also produces numerous and fragmented branches, or tendrils, at the swarm front. Whereas additional surfactants enhance swarming, increasing the agar percentage, adding extra salt or sugar or incorporating viscous agents in the agar matrix all decrease swarming, supporting the conclusion that swarming motility is restricted by the surface tension at the swarm front and swarm growth is limited by the rate of water supply from within the agar gel. The physical basis elaborated through this study provides a useful framework for understanding the swarming behavior of numerous species of bacteria.

Canalicular laceration repair with a novel viscoelastic injection technique to locate and dilate the proximal torn edge

Canalicular lacerations are common complications of eyelid trauma in the pediatric population. Irrigating air, water, colored or viscous agents through the intact canaliculus have been suggested to make locating the torn proximal edge easier. We report our experience in repairing canalicular lacerations using a novel viscoelastic injection technique with a Monoka monocanalicular stent.

Effect of Viscous Agents on Corneal Density in Dry Eye Disease.

To investigate the effect of the viscous agents, hydroxypropyl methylcellulose (HPMC), carbomer, povidone, and a combination of HPMC and povidone on corneal density in patients with dry eye disease. In total, 98 eyes of 49 patients suffering from dry eye and 65 eyes of 33 healthy age-matched individuals were included in this prospective, randomized study. Corneal morphology was documented with Scheimpflug photography and corneal density was analyzed in 5 anatomical layers (epithelium, bowman membrane, stroma, descemet's membrane, and endothelium). Corneal density was evaluated for the active ingredients HPMC, carbomer, povidone, and a combination of HPMC and povidone as the viscous agents contained in the artificial tear formulations used by the dry eye patients. Data were compared to the age-matched healthy control group without medication. Corneal density in dry eye patients was reduced in all 5 anatomical layers compared to controls. Corneal density was highest and very close to control in patients treated with HPMC containing ocular lubricants. Patients treated with lubricants, including carbomer as the viscous agent displayed a significant reduction of corneal density in layers 1 and 2 compared to control. HPMC containing ocular lubricants can help to maintain physiological corneal density and may be beneficial in the treatment of dry eye disease.

Canalicular laceration repair using a viscoelastic injection to locate and dilate the proximal torn edge.

Canalicular lacerations are common complications of eyelid trauma in the pediatric population. Irrigating air, water, and colored or viscous agents through the intact canaliculus have been suggested to identify the torn proximal edge. We report our experience in repairing canalicular lacerations using a novel viscoelastic injection technique with a Monoka monocanalicular stent. The medical records of patients <18 years of age who underwent repair of a canalicular laceration with a monocanalicular stent using superficial viscoelastic deployment to locate the torn canaliculus were retrospectively reviewed. Demographics, cause of eyelid injury, surgical management using our novel viscoelastic injection technique, and outcome were analyzed. A total of 38 children with lid lacerations were identified, of whom the 17 with canalicular involvement were included (mean age, 6.27 years). Canalicular injury in these 17 was due to dog bite (9 patients) and shearing trauma (8 patients). In 11 patients, the injury was located in the lower lid; in 4, the upper lid; and in 2, combined upper and lower lids. All patients had good anatomic repair and on follow-up had negative dye disappearance tests and were free of tearing. Deploying viscoelastic superficially near, and injecting into the injured canaliculus can improve visualization of the operative field by retracting the surrounding tissue and tamponading any bleeding, which aids in location and dilation of the torn canaliculus initially and in subsequent steps, eases intubation into the lubricated torn canaliculus and nasolacrimal duct, and avoids iatrogenic injury to an uninjured canaliculus.

Study on the Addition of Viscous Agents to Fish-Boat-Fuel in Real Ship Trials

This study adopted a new formula fishing-boat fuel which is based on the existing fishing-boat-fuel A (FBFA) with the addition of viscous agents (RDS0.5, PFO0.5) in two different proportions. FBFA, RDS0.5 and PFO0.5, respectively are tested in three real-scale fishing boats. During the actual ship trial, the engine operating conditions, engine fuel oil consumption, horse power output and navigation speed were assessed and recorded. Furthermore, fuel emissions were sampled and analyzed, fishing-boat diesel engine performance was assessed and differences in exhaust composition were compared. The results showed that the three new viscous agents fules used lack abnormal vibration and noise, and have similar output status in terms of engine operational performance. At the same boat, the fuel oil consumption rates were similar between the new formula and FBFA. Moreover, analysis of contamination displayed that RDS0.5 particulate matter (PM) content was less than that of FBFA. Consequently, RDS0.5 appears to cause less engine wear. Additionally, the exhaust emission analysis results identified RDS0.5 as the best fuel for the engine. Futhermore, regarding pollutant emissions, including CO, CO2, NOx, PM, PAHs, only CO emissions are slightly higher than for FBFA. However, the CO emission value does not exceed exhaust emission standards of the U.S. Environmental Protection Agency (EPA). It is remains within the allowable value range. RDS0.5 should have practical value.

Das trockene Auge in der Frauenheilkunde

The clinical diagnosis of dry eye syndrome may not appear to be a major health problem; nonetheless it is a chronic condition which affects several million people in Germany. Typical symptoms include discomfort, dryness, foreign body sensation, photophobia and light sensitivity, and it is associated with a significant reduction in the quality of life. Physiological changes associated with aging include decreased tear volume and flow , decreased tear film stability and alterations in the composition of the meibomian lipids and are correlated with tear film dysfunction. According to more recent studies into the role of tear film dysfunction in dry eye syndrome, estrogen - which has a clear role in the treatment of various menopausal symptoms - may have an adverse effect on the ocular surface and may predispose to dry eye syndrome. Dry eye syndrome is classified into two major categories: tear deficient dry eye and evaporative dry eye, each of which requires specific treatment. Therapeutic approaches include ocular lubricants and/or viscous agents to restore or increase the lipid layer of the tear film.

Emissions in the exhaust of fishing boats after adding viscous agents into fuel oils

In order to avoid the illegal use of fishing boat fuel A (FBFA) by traveling diesel vehicles (TDVs) in Taiwan, alternatives that are easily distinguished from premium diesel fuel (PDF) were prepared to evaluate their suitability. Two new ingredients, pyrolysis fuel oil (PFO) and residue of desulfurization unit (RDS), were added into FBFA and formed PFO0.5 and RDS0.5, respectively. Along with FBFA, these three fuels were analyzed for their chemical and physical properties. Furthermore, they were used by three fishing boats with different sizes, output powers, and weights. The engine performances and pollutant emissions were examined and monitored. Experimental results show that there are significant differences in appearance between PDF and the two new blended fuels (PFO0.5 and RDS0.5), and thus misuse or illegal use of FBFA could be substantially reduced. The fuel consumption, which is negatively related to the heating value of fuels, is in order of FBFA < PFO0.5 = RDS0.5. In contrast with using FBFA in the three fishing boats, using RDS0.5 resulted in a decrease in CO and NO x emissions, while the PM emission factors (g bhp − 1 h − 1 and g L − 1 -fuel) were reduced by approximately 36% and 33%, respectively. Owing to the higher total aromatic content in PFO0.5 and RDS0.5, total-PAH concentrations in the exhausts from the three fishing boats using PFO0.5 and RDS0.5 were slightly (1.2 and 1.1 times, respectively) higher than for those using FBFA. Nevertheless, the estimated total BaP eq from the three fishing boats using RDS0.5 was 27.5, 19.5, and 8.25% lower than those using FBFA. With using PFO0.5, they were totally different, at 23.5, 2.79, and 2.58% higher. With regard to looking different to PDF, RDS0.5 is superior to PFO0.5, and is thus recommended as a better alternative to FBFA, particularly because it can help lower more emissions of CO, NO x , PM and BaP eq.

Continuous phase viscosity influence on maximum diameters of poly(styrene-divinylbenzene) beads prepared by suspension polymerization

The influence of the continuous phase viscosity (μc) on the diameter of styrene-divinylbenzene polymer beads was studied over a large range of viscosities at constant dissipated power. This study was based on the inertial breakup and viscous shear breakup theories for a stirred dispersion. These two theoretical models were compared with an experiment for the two highly viscous agents sucrose and acacia gum [dispersed and continuous phase viscosities (μd, μc) = 10−3 < μd/μc < 1]. We found that the maximum diameters of the polymer beads could not be described by an inertial breakup. The maximum diameters were in good agreement with a viscous shear breakup model for the two viscous agents in turbulent and semilaminar flows. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 201–210, 2001

2PD040 粘性物質添加による細菌べん毛の推進効率向上

2PD040 粘性物質添加による細菌べん毛の推進効率向上

The sodium-driven polar flagellar motor of marine Vibrio as the mechanosensor that regulates lateral flagellar expression.

Certain marine Vibrio species swim in sea water, propelled by a polar flagellum, and swarm over surfaces using numerous lateral flagella. The polar and the lateral flagellar motors are powered by sodium- and proton-motive forces, respectively. The lateral flagella are produced in media of high viscosity, and the relevant viscosity sensor is the polar flagellum. The cell might monitor either the rotation rate of the flagellar motor or the mechanical force applied against the flagellum. To test these possibilities, we examined the effects of amiloride and its derivatives, which inhibit the rotation of the sodium-driven motor, on lateral flagellar gene (laf) expression in Vibrio parahaemolyticus. Phenamil, an amiloride analogue that inhibits swimming at micromolar concentrations, induced laf transcription in media devoid of viscous agents in a dose-dependent manner. The relationship between the average swimming speed and laf induction in the presence of various concentrations of phenamil was very similar to that observed when viscosity was changed. These results indicate that marine Vibrio sense a decrease in the rotation rate of (or the sodium influx through) the polar flagellar motor as a trigger for laf induction. Alternative mechanisms for laf induction are also discussed.

A Mutant Hook-associated Protein (HAP3) Facilitates Torsionally Induced Transformations of the Flagellar Filament of Escherichia coli

Two mutants with defects in hook-associated protein 3 (HAP3) were isolated that exhibit impaired swimming only when they interact with a solid surface or a semisolid matrix. Motility and chemotaxis were normal in liquid media, even in media containing viscous agents, but cells failed to swarm in 0·28% agar. Mutants appeared to carry a full complement of flagella of normal configuration and length. However, filaments rotating counterclockwise close to a glass surface transformed from normal to straight, while filaments rotating clockwise transformed from curly to straight. Both transformations propagated from base to tip, as expected if torsionally induced. The mutations mapped to the middle of flgL, the structural gene for HAP3, and sequence analysis revealed the same coding change in both mutants: a substitution of cysteine for arginine 168. Our results show that the ability of a filament composed of normal flagellin subunits to resist mechanical stress depends on the structure of the protein (HAP3) to which is attached at its base. The N-terminal sequence of HAP3 was found to be similar to the N-terminal sequence of flagellin, and the possibility that it provides a nucleation site for the C-terminal region of flagellin is discussed.

Evaluations on the Usefulness of Viscous Agents in Anterior Segment Surgery. II. Effect on Intraocular Pressure and Clearance from the Anterior Chamber

Various viscous agents in anterior segment surgery were replaced with the aqueous humor of rabbit eyes. The effects of these agents on intraocular pressure (IOP) and their clearance from the anterior chamber were studied. Furthermore, the degradation of these agents in ocular and hepatic tissues was investigated. The IOP after the injection of a 1% solution of sodium hyaluronate with a molecular weight of 790 x 10(3) (Na-HA (790 x 10(3), 1%], fell to the normal level after 12 hours; however, after a 1% solution of sodium hyaluronate with a molecular weight of 2160 x 10(3) (Na-HA (2160 x 10(3), 1%], a 2% solution of methylcellulose with a molecular weight of 86 x 10(3) (MC (86 x 10(3), 2%] or a 30% solution of sodium chondroitin sulfate with a molecular weight of 30 x 10(3) (Na-Chs (30 x 10(3), 30%], the return of IOP to normal level required 24 hours. Six hours after the injection of MC (86 x 10(3), 2%), the IOP was significantly higher than those of other agents. Na-Chs (30 x 10(3), 30%) and Na-HA (790 x 10(3), 1%) were eliminated from the anterior chamber within 12 and 24 hours, respectively. Na-HA (2160 x 10(3), 1%) and MC (86 x 10(3), 2%) required 72 hours to be eliminated from the anterior chamber. The degradation of Na-HA was detected in extracts of the iris, corneo-scleral junction, and liver. The degradation of Na-Chs was also detected in the liver extract, but the degradation of MC was not detected. On the basis of these findings, and the results in our previous report with respect to the efficacy of the viscous agents, it is concluded that Na-HA is the best viscous agent to be used in anterior segment surgery.

Simultaneous Determination of Anionic Surfactants and Inorganic Electrolytes by an Isotachophoretic Method

An isotachophoretic method for the simultaneous determination of anionic surfactants and inorganic electrolytes in aqueous solutions was investigated. This method is based on the pH of leading electrolytes, species of terminating ions, species and concentration of viscous agents. The optimum conditions for the simultaneous determination were found to be 5 mM HC1-10-2% HPMC/Trishydroxymethylaminomethane (pH 8.5) as the leading electrolyte and 5 mM β-Alanine/KOH (pH 10.4) as the terminating electrolyte. Isotachophoretis also proved quite useful for the simultaneous determination of detergent ingredients.

Fatigue crack growth of PMMA in organic agents

Crack growth tests under cyclic loading were executed at 295 K in various organic agents using compact tension and pure bending specimens of polymethylmethacrylate (PMMA). The cyclic frequencies f for the two kinds of test were 0.4 to 1 and 33 Hz, respectively. Two interesting features are pointed out: (i) transitional behaviour is observed on a crack growth rate against stress intensity factor range ΔK diagram, and (ii) the fatigue fracture surfaces tested in highly viscous agents are covered with a new type of striation named “wavy striation”, as reported previously. The crack growth rate at the transition was analysed based on fluid flow through the pores within the craze forming at the crack tip. The wavy striation was also investigated by use of the theory of meniscus instability. It is found that both the phenomena may be well described by a parameter P = T(ΔK)2/ηf where T and η are the surface tension and viscosity of the organic agents, respectively.