Adsorption and Aggregation Properties of Homogeneous Polyoxypropylene–Polyoxyethylene Alkyl Ether Type Nonionic Surfactants

Homogeneous polyoxypropylene (PO)–polyoxyethylene (EO) alkyl ether type nonionic surfactants comprising alkyl, EO, and PO chains with identical chain length distributions (C_<i>n</i>EO_<i>x</i>PO_<i>y</i>; alkyl chain length <i>n</i> = 10, 12, 14, or 16; EO chain length <i>x</i> = 4, 6, or 8; and PO chain length <i>y</i> = 1, 2, or 3) were synthesized from homogeneous polyoxyethylene alkyl ether bromide and monosodium polyoxypropylene by Williamson ether synthesis. The adsorption and aggregation properties of these surfactants were characterized (cloud point, surface tension, dynamic light scattering, small-angle X-ray scattering, polarization microscopy, and cryogenic transmission electron microscopy) and compared to those of conventional homogeneous EO alkyl ether type nonionic surfactants (C_<i>n</i>EO_<i>x</i>). The introduction of a PO chain to the EO terminal group of the C_<i>n</i>EO_<i>x</i> species lowered the cloud points, especially for <i>x</i> = 6. Contrary to our expectations, the C_<i>n</i>EO_<i>x</i>PO_<i>y</i> surfactants adsorbed efficiently at the air/water interface, despite their complex structure (hydrophobic alkyl chain/hydrophilic EO chain/hydrophobic PO chain). They also displayed excellent micelle-forming ability in solution. Furthermore, the C_<i>n</i>EO_<i>x</i> species formed small micelles in solution at low concentrations and the structures transformed to hexagonal liquid crystals as the surfactant concentration increased. Conversely, C_<i>n</i>EO_<i>x</i>PO_<i>y</i> maintained a micellar structure even at high concentrations. Notably, the introduction of a PO chain into the C_<i>n</i>EO_<i>x</i> surfactant controlled the formation of aggregates with a higher-order structure (hexagonal liquid crystals)

A clinical study of peroral endoscopic myotomy reveals that impaired lower esophageal sphincter relaxation in achalasia is not only defined by high-resolution manometry - Fig 3

<p>(a) Endoscopy showing a totally dilated esophagus. (b) Esophagography showing sigmoid-like appearance with retention of contrast medium. (c) High-resolution manometry showing 100% failed peristalsis (type-I achalasia) with normal integrated relaxation pressure (18.5 mmHg).</p

Patient characteristics.

<p>Patient characteristics.</p

A clinical study of peroral endoscopic myotomy reveals that impaired lower esophageal sphincter relaxation in achalasia is not only defined by high-resolution manometry - Fig 7

<p>(a) Grading of lower esophageal sphincter (LES) fibrosis in the integrated relaxation pressure (IRP) > 26 mmHg subgroup (n = 21) and IRP ≤ 26 mmHg subgroups (n = 11). (b) Cases of severe fibrosis (grade 3) in the LES were only observed in the IRP ≤ 26 mmHg subgroup. Azan-Mallory staining (200×magnification) revealing severe atrophic changes with replacement by fibrosis in the smooth muscle bundles (yellow triangle). Fibrotic tissue extension in the inter-smooth muscle bundles is also seen (red triangle).</p

A clinical study of peroral endoscopic myotomy reveals that impaired lower esophageal sphincter relaxation in achalasia is not only defined by high-resolution manometry - Fig 5

<p>Spearman's correlation coefficient to determine the correlation between integrated relaxation pressure (IRP) and age (Fig 5a) or IRP and symptom duration (Fig 5b), calculated as -0.308 (P = 0.05) and -0.371 (P = 0.02), respectively. The dotted horizontal line means IRP = 26 mmHg, whereas the red solid line shows the linear regression of all measurements of patients in the IRP > 26 mmHg and IRP ≤ 26 mmHg groups. (c) IRP was higher in patients with non-dilated esophagus than in those with dilated esophagus (P < 0.01). Bars indicate median values.</p

A clinical study of peroral endoscopic myotomy reveals that impaired lower esophageal sphincter relaxation in achalasia is not only defined by high-resolution manometry - Fig 2

<p>(a) Endoscopy showing a mucosal pinstripe pattern with increased resistance through the esophago-gastric junction.[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0195423#pone.0195423.ref011" target="_blank">11</a>] (b) On esophagography, bird-beak appearance and remnant barium in a non-dilated esophagus were observed. (c) High-resolution manometry showing 100% failed peristalsis (type-I achalasia) with normal integrated relaxation pressure (22.9 mmHg).</p

A clinical study of peroral endoscopic myotomy reveals that impaired lower esophageal sphincter relaxation in achalasia is not only defined by high-resolution manometry - Fig 6

<p>(a) Changes in the Eckardt score before and after peroral endoscopic myotomy (POEM) in the integrated relaxation pressure (IRP) > 26 mmHg group (pre-op Eckardt score 7 ± 2.1 vs. post-op 1 ± 0.9, P < 0.01) and IRP ≤ 26 mmHg group (pre-op 7 ± 2.6 to 1 ± 0.6, P < 0.01). (b) Changes in IRP (mmHg) before and after POEM in the IRP >26 mmHg subgroup (pre-operative 38.6 ± 13.3 vs. post-operative 8.9 ± 5.3 mmHg, P < 0.01) and IRP ≤ 26 mmHg subgroup (pre-operative 21.5 ± 5.0 vs. post-operative 9.9 ± 4.0 mmHg, P < 0.01).</p

A clinical study of peroral endoscopic myotomy reveals that impaired lower esophageal sphincter relaxation in achalasia is not only defined by high-resolution manometry - Fig 1

<p>(a) On endoscopy, the esophagus looks normal without dilation. However, increased resistance was observed through the esophago-gastric junction in a patient with achalasia. (b) Esophagography showing a bird-beak appearance with remnant barium in a non-dilated esophagus. (c) High-resolution manometry showing pan-esophageal pressurization (type-II achalasia) with elevated integrated relaxation pressure (IRP) (43.3 mmHg; the IRP measurement was taken after deglutitive upper sphincter relaxation, based on the 4-s window in which the e-sleeve value is lowest, noting that the 4 s did not have to be continuous, but could be distributed within a 10 s time window (white closing box).</p

Flowchart of patient enrollment.

<p>From 61 cases of peroral endoscopic myotomy, 20 cases were excluded and 41 patients with achalasia were finally enrolled. Thereafter, twenty-seven achalasia patients were categorized into a subgroup with integrated relaxation pressure (IRP) > 26 mmHg (impaired lower esophageal sphincter [LES] relaxation on high-resolution manometry [HRM]), whereas 14 were placed into the IRP ≤ 26 mmHg group (normal LES relaxation on HRM).</p

Additional file 1 of Trends in survival during the pandemic in patients with critical COVID-19 receiving mechanical ventilation with or without ECMO: analysis of the Japanese national registry data

Additional file 1: Table 1. Activities of the Japan ECMO networ