Ultrasound examination of the normal fetal duodenum.

Objective: To use the fetal pylorus as a reference point to conveniently display the normal fetal duodenum by ultrasound. Methods: This study was designed in cross-section. A total of 450 healthy singleton pregnant women at 19-39 weeks of gestation who underwent prenatal screening at our hospital from January 2019 to February 2020 were selected. They were divided into three groups according to gestational weeks: the 19-23 gestational weeks group, 29-32 gestational weeks group, and 34-39 gestational weeks group. The duodenal bulb was identified. Its movement and course were continuously and dynamically observed. The descending part of the duodenum was identified, and the duodenal course was traced. Results: The fluid-filled in the fetal duodenum was discontinuous. The overall detection rates of the duodenum in the 19-23 gestational weeks group, 29-32 gestational weeks group, and the 34-39 gestational weeks group were 82.2%, 26.2%, and 13.8%, respectively. The detection rates of the bulbar, descending, horizontal, and ascending parts of the duodenum were 94.4%, 58.2%, 58.0%, and 52.0%, respectively. The anatomical structures of the duodenum as a whole and the pancreas were most easily recognized in the 19-23 gestational weeks group; while in the 34-39 gestational weeks group, the bulbar part had a maximum detection rate of 98.8%, and it had the longest filling time and the shortest examination time. Conclusion: The pylorus is an ideal starting point for tracing the fetal duodenum. The overall detection rate of the fetal duodenum decreases with gestational age. The duodenal bulb is the most easily detected site.

Meso-scale dislocations and friction of shape-complementary soft interfaces.

The interface between two surfaces patterned with complementary shapes such as arrays of ridge-channel structures or pillars accommodates relative misorientation and lattice mismatch by spontaneous production of dislocation arrays. Here, we show that the relative sliding of such an interface is accomplished by dislocation glide on the interfacial plane. An exception is the singular case where the lattices are perfectly matched across the sample dimension, in which case sliding is accompanied by motion of edge-nucleated defects. These are meso-scale analogues of molecular sliding friction mechanisms between crystalline interfaces. The dislocations, in addition to the long-range elastic energy associated with their Burgers vectors, also cause significant out-of-plane dilation, which props open the interface locally. For this reason, the sliding friction is strongly pressure dependent; it also depends on the relative orientation of the patterns. Sliding friction can be strongly enhanced compared with a control, showing that shape-complementary interfaces can be engineered for strongly enhanced pressure- and orientation-dependent frictional properties in soft solids.

Intrinsically reversible superglues via shape adaptation inspired by snail epiphragm.

Adhesives are ubiquitous in daily life and industrial applications. They usually fall into one of two classes: strong but irreversible (e.g., superglues) or reversible/reusable but weak (e.g., pressure-sensitive adhesives and biological and biomimetic surfaces). Achieving both superstrong adhesion and reversibility has been challenging. This task is particularly difficult for hydrogels that, because their major constituent is liquid water, typically do not adhere strongly to any material. Here, we report a snail epiphragm-inspired adhesion mechanism where a polymer gel system demonstrates superglue-like adhesion strength (up to 892 N⋅cm-2) that is also reversible. It is applicable to both flat and rough target surfaces. In its hydrated state, the softened gel conformally adapts to the target surface by low-energy deformation, which is locked upon drying as the elastic modulus is raised from hundreds of kilopascals to ∼2.3 GPa, analogous to the action of the epiphragm of snails. We show that in this system adhesion strength is based on the material's intrinsic, especially near-surface, properties and not on any near-surface structure, providing reversibility and ease of scaling up for practical applications.

Indentation versus Rolling: Dependence of Adhesion on Contact Geometry for Biomimetic Structures.

Numerous biomimetic structures made from elastomeric materials have been developed to produce enhancement in properties such as adhesion, static friction, and sliding friction. As a property, one expects adhesion to be represented by an energy per unit area that is usually sensitive to the combination of shear and normal stresses at the crack front but is otherwise dependent only on the two elastic materials that meet at the interface. More specifically, one would expect that adhesion measured by indentation (a popular and convenient technique) could be used to predict adhesion hysteresis in the more practically important rolling geometry. Previously, a structure with a film-terminated fibrillar geometry exhibited dramatic enhancement of adhesion by a crack-trapping mechanism during indentation with a rigid sphere. Roughly isotropic structures such as the fibrillar geometry show a strong correlation between adhesion enhancement in indentation versus adhesion hysteresis in rolling. However, anisotropic structures, such as a film-terminated ridge-channel geometry, surprisingly show a dramatic divergence between adhesion measured by indentation versus rolling. We study this experimentally and theoretically, first comparing the adhesion of the anisotropic ridge-channel structure to the roughly isotropic fibrillar structure during indentation with a rigid sphere, where only the isotropic structure shows adhesion enhancement. Second, we examine in more detail the anomalous anisotropic film-terminated ridge-channel structure during indentation with a rigid sphere versus rolling to show why these structures show a dramatic adhesion enhancement for the rolling case and no adhesion enhancement for indentation.

Spontaneous Droplet Motion on a Periodically Compliant Substrate.

Droplet motion arises in many natural phenomena, ranging from the familiar gravity-driven slip and arrest of raindrops on windows to the directed transport of droplets for water harvesting by plants and animals under dry conditions. Deliberate transportation and manipulation of droplets are also important in many technological applications, including droplet-based microfluidic chemical reactors and for thermal management. Droplet motion usually requires gradients of surface energy or temperature or external vibration to overcome contact angle hysteresis. Here, we report a new phenomenon in which a drying droplet placed on a periodically compliant surface undergoes spontaneous, erratic motion in the absence of surface energy gradients and external stimuli such as vibration. By modeling the droplet as a mass-spring system on a substrate with periodically varying compliance, we show that the stability of equilibrium depends on the size of the droplet. Specifically, if the center of mass of the drop lies at a stable equilibrium point of the system, it will stay there until evaporation reduces its size and this fixed point becomes unstable; with any small perturbation, the droplet then moves to one of its neighboring fixed points.

Interaction of Droplets Separated by an Elastic Film.

The Laplace pressure of a droplet placed on one side of an elastic thin film can cause significant deformation in the form of a bulge on its opposite side. Here, we show that this deformation can be detected by other droplets suspended on the opposite side of the film, leading to interaction between droplets separated by the solid (but deformable) film. The interaction is repulsive when the drops have a large overlap and attractive when they have a small overlap. Thus, if two identical droplets are placed right on top of each other (one on either side of the thin film), they tend to repel each other, eventually reaching an equilibrium configuration where there is a small overlap. This observation can be explained by analyzing the energy landscape of the droplets interacting via an elastically deformed film. We further demonstrate this idea by designing a pattern comprising a big central drop with satellite droplets. This phenomenon can lead to techniques for directed motion of droplets confined to one side of a thin elastic membrane by manipulations on the other side.

Strongly Modulated Friction of a Film-Terminated Ridge-Channel Structure.

Natural contacting surfaces have remarkable surface mechanical properties, which has led to the development of bioinspired surface structures using rubbery materials with strongly enhanced adhesion and static friction. However, sliding friction of structured rubbery surfaces is almost always significantly lower than that of a flat control, often due to significant loss of contact. Here we show that a film-terminated ridge-channel structure can strongly enhance sliding friction. We show that with properly chosen materials and geometrical parameters the near surface structure undergoes mechanical instabilities along with complex folding and sliding of internal interfaces, which is responsible for the enhancement of sliding friction. Because this structure shows no enhancement of adhesion under normal indentation by a sphere, it breaks the connection between energy loss during normal and shear loading. This makes it potentially interesting in many applications, for instance in tires, where one wishes to minimize rolling resistance (normal loading) while maximizing sliding friction (shear loading).

Template-assisted GLAD: approach to single and multipatch patchy particles with controlled patch shape.

Template-assisted glancing angle deposition (GLAD) is explored for the fabrication of single and multipatch patchy particles with one or more patches of controlled but asymmetric shape. The template is used to ensure the formation of uniform patchy particles, whereas rotation of the template gives access to a large number of asymmetric patch shapes caused by the shadowing effect of the templating groove and/or the neighboring particle. Careful analysis with a straightforward geometric model reveals the effect of the angle of incidence, rotational angle, groove size, and particle size on the patch shape. Initial magnetic field assembly results are presented to illustrate the removal of patchy particles from their template and accessibility to a large number of patchy particles. Two-patch particles with overlapping patches are also accessible by means of secondary metal vapor deposition. The connectivity of these two patches on each particle and the predictable size of the overlapping section provide access to functional patchy particles. The combination of the template-assisted GLAD method with rotation of the template and secondary evaporation is demonstrated to be a good method for fabricating patchy particles with a variety of asymmetric patch shapes, sizes, and multipatches where every particle of a batch carries exactly the same patch pattern and thereby provides valuable input on experimentally accessible patch shapes for future experimental and computational studies of patchy particles.

Template-assisted fabrication of patchy particles with uniform patches.

Patchy particles with uniform patches of specific shape and size have been predicted to have a rich potential in fabricating new structures; however, an effective method to control the patch shape and size is still missing. In the method presented here, a template is used to assist the fabrication of patchy particles with patches of uniform shape and controlled size by use of the glancing angle deposition method (GLAD). Uniform shadowing effects are caused by the wall of the grooves carved into the surface of a silicon wafer. The ratio of template dimension to particle diameter and the angle of incidence of the metal vapor rays determine the patch shape and size. Mathematical calculations are applied to predict the patch shape and size. Scanning electron microscopy is used to demonstrate the efficiency of the method. Scaling analysis shows that the template-assisted GLAD method leads to a 3100-fold increase in patchy particle fabrication volumes compared to the template-free GLAD method.

Evaluation of ghost cell survival in the area of radiofrequency ablation.

BACKGROUND AND AIM: Researchers have demonstrated dead cells in radiofrequency ablation (RFA) lesions that have morphological similarities to viable tumor cells and are thus referred to as ghost cells. However, studies on how long ghost cells persist have not been systematically performed. METHODS: A tumor model was established by implanting VX2 tumor tissue into the livers of 48 New Zealand rabbits. Two weeks later, these tumors were eliminated with RFA. The lesions were resected at 0 weeks, 1 week, 2 weeks, 4 weeks, 8 weeks, or 12 weeks after treatment, and samples were stained either with hematoxylin and eosin (HE) or nicotinamide adenine dinucleotide (NADH). The presence of the cells and the morphological changes that they underwent were examined by light microscopy. RESULTS: Four weeks after RFA, there were no obvious morphological changes observed in HE-stained ghost cells, and NADH staining revealed no viable cells. Eight weeks after RFA, the cell structure became indistinct. Twelve weeks after RFA, ghost cells were no longer present. CONCLUSIONS: The morphological characteristics of ghost cells are maintained for at least 4 weeks, during which time HE staining cannot be used to differentiate ghost cells from residual tumor cells. NADH staining for cell viability is necessary to differentiate residual tumor cells from ghost cells. This evidence adds to our understanding of the mechanisms of RFA when used on solid tumors.

Safety and reliability of hepatic radiofrequency ablation near the inferior vena cava: an experimental study.

PURPOSE: The heat-sink effect produced by rapid blood flow through large vessels (diameter (D) ≥ 5 mm) is an important factor that influences ablation zone size after radiofrequency ablation (RFA). Currently, however, the interactions between hepatic RFA lesions and large vessels are not well understood. The purpose of this study was to examine the effects of RFA lesions occurring near large vessels (D ≥ 5 mm) in the canine liver. MATERIALS AND METHODS: Thirty healthy adult mongrel dogs were used, with 15 dogs randomly assigned to groups I and II. In group I, the closest distance from the tip of the RFA electrode to the large vessel (D ≥ 5 mm) was more than 20 mm; in group II, this distance to the wall of the inferior vena cava (IVC) was no more than 5 mm. RFA was performed on the liver of each dog according to standard procedures. The blood flow velocity of the IVC, the computerised tomography (CT), the pathological characteristics of the RFA lesions and procedure-related complications were examined. RESULTS: No death or complications occurred in any dogs. Vascular walls were not affected, except for when the tips of the electrode stuck to the IVC. The coagulative necrosis region was decreased, and its shape was fusiform close to the IVC. Some normal hepatic cells were found in the necrotic region near the IVC. CONCLUSIONS: It is both safe and feasible to perform RFA near the IVC. The shape and size of the coagulation zone should be considered when electrodes are placed in this area. Near the IVC, the size of the coagulation zone was decreased, and it was incompletely formed.

[Observation on experimental liver fibrosis and hepatic carcinogenesis of HBV gene knock-in transgenic mice induced by CCl4/ethanol].

OBJECTIVE: To study the effects of carbon tetrachloride (CCl4)/ethanol induction upon experimental liver fibrosis and hepatic carcinogenesis of HBV transgenic mice. METHODS: The wild-type mice, p21-HBx transgenic mice with integration of p21 locus by HBx gene and p21-HBsAg transgenic mice with integration of p21 locus by HBsAg gene were induced separately by CCl4/ethanol twice weekly for 20 weeks. The investigators observed the development of liver fibrosis and hepatic carcinogenesis in three groups and detected the gene expressions of HBx and HBsAg by RT-PCR. RESULTS: The expression of HBx or HBsAg mRNA existed in both control and induced transgenic mice, but in none of wild-type mice. Comparing with wild-type mice, p21 genes was not expressed in livers of transgenic mice. After induction by CCl4/ethanol, the fibrotic degrees of liver were not significantly different among wild-type mice, p21-HBx transgenic mice and p21-HBsAg transgenic mice, as well as between male and female mice. Reversely, the incidence rates of hepatic carcinogenesis of two HBV gene knock-in transgenic mouse lines (p21-HBx & p21-HBsAg) were higher than that of wild-type mice. And the incidence rate of hepatic carcinogenesis in males was also markedly higher than that in females. Induction by CCl4/ethanol markedly promoted and accelerated hepatic carcinogenesis in transgenic mice. CONCLUSIONS: Integration of HBsAg and HBx genes into the murine p21 locus can significantly promote the progression of hepatic carcinogenesis, but failed to promote the progression of liver fibrosis. The male mouse is more likely to develop experimental hepatocellular carcinoma than the female mouse. Experimental hepatocellular carcinoma induced by CCl4/ethanol in p21-HBx and p21-HBsAg transgenic mice is a feasible animal model.

[Effects of Smad4 on liver fibrosis and hepatocarcinogenesis in mice treated with CCl4/ethanol].

To study the effects of Smad4 on liver fibrosis and hepatocarcinogenesis in mice treated with CCl(4)/ethanol. The wild-type mice (Smad4 +/+) and the Smad4 knockout mice (Smad4 +/-) were injected subcutaneously with carbon tetrachloride(CCl(4))/ethanol twice a week for twenty weeks. The expression of Smad4, TGFbeta1, Smad2, Smad3, Smad6, TIMP1, MMP2 and MMP9 was detected by RT-PCR. In the cirrhotic liver, the expression of Smad4 mRNA was significantly higher than that in the normal liver. Comparing with wild-type mice (Smad4 +/+), the TGFbeta1-Smad4 signaling was markedly attenuated in the Smad4 knockout mice (Smad4 +/-). After induction by CCl(4)/ethanol, the hepatic fibrosis in the Smad4 knockout mice (Smad4 +/-) was obviously alleviated compared with the wild-type mice (Smad4 +/+), and the incidence rate of hepatocarcinogenesis of the former was also lower than that of the latter(32.0% vs 41.9%). These results indicate that knocking out Smad4 can delay the progression of liver fibrosis and liver cancer.

Modulating the catalytic activity of Au/micelles by tunable hydrophilic channels.

Polymeric micelles with a polystyrene core, poly(acrylic acid)/poly(4-vinyl pyridine) (PAA/P4VP) complex shell and poly(ethylene glycol) & poly(N-isopropylacrylamide) (PEG & PNIPAM) mixed corona were synthesized and used as the supporter for the gold nanoparticles (GNs). It was concluded from the result of (1)H NMR characterization that hydrophilic channels formed around PEG chains when PNIPAM collapsed above its lower critical solution temperature. The density of the channels in the corona can be tuned by changing the weight ratios of PEG chains to PNIPAM chains. The GNs were set in the PAA/P4VP complex layer and the catalytic activity of the GNs can be modulated by the channels. The catalytic activity increased with increasing the density of the channels in the corona. Meanwhile, the whole Au/micelle nanoparticles were stabilized by the extended PEG chains.

[Surgical treatment for hilar cholangiocarcinoma of Bismuth-Corlette type IV].

OBJECTIVE: To investigate the surgical treatment for hilar cholangiocarcinoma(HCCA) of Bismuth-Corlette type IV. METHODS: The clinical data of 73 HCCA patients admitted in Southwest Hospital, the Third Military Medical University from January 2002 to December 2008 were analyzed retrospectively. There were 41 males and 32 females, aged from 30 to 84 years old (averaged, 56.8 years old). All patients were diagnosed as hilar mass with hilar biliary obstruction by B-ultrasound, CT, magnetic resonance imaging, endoscopic retrograde cholangiopancreatography, magnetic resonance cholangiopancreatography or percutaneous transhepatic cholangiography, and confirmed by pathological examination in intra-operation and post-operation. Diagnosis of all patients were according to Bismuth-Corlette type IV. RESULTS: Fifteen cases underwent percutaneous transhepatic cholangial drainage, stents were implanted in 8 patients. Simple internal drainage was performed on 25 of the 73 patients and 4 with palliative resection. Radical resection was performed on 19 patients. The radical resection rate of HCCA were 26.0%. The 1, 3 years of survival rates were 36.8%, 10.5% respectively. The 1 year survival rate was 6.3% in drainage group. CONCLUSION: Radical resection is the potentially curative treatment for HCCA, a sufficient, reasonable use of internal and external drainage would improve the patient's quality of life.

Core-shell-corona au-micelle composites with a tunable smart hybrid shell.

Micelles having a core of polystyrene and a mixed shell of poly(ethylene glycol) and poly(4-vinylpyridine) were formed through self-assembly of a triblock copolymer poly(ethylene glycol)- block-polystyrene- block-poly(4-vinylpyridine) in acidic water (pH 2). Reducing the HAuCl(4)-treated micelle solution leads to the formation of the Au-micelle composites with a core of polystyrene, a hybrid shell of poly(4-vinylpyridine)/Au/poly(ethylene glycol), and a corona of poly(ethylene glycol). The gold nanoparticles with controlled sizes were anchored to poly(4-vinylpyridine) to form the physically cross-linked hybrid shell. In aqueous solution, the hybrid shell is swollen and the swollen degree is sensitive to the pH condition. Under basic conditions, the channel in the hybrid shells of the composite is produced, which renders the composites a good catalytic activity. In addition, the composites also show good stability, unchanged hydrodynamic diameter, and surface plasmon absorption under different pH conditions.

Two-year follow-up of splenic radiofrequency ablation in patients with cirrhotic hypersplenism: does increased hepatic arterial flow induce liver regeneration?

BACKGROUND: Hepatocyte hypoxia may be a mechanism determining abnormal tissue oxygenation and dysfunction of the cirrhotic liver. Since the introduction of radiofrequency ablation (RFA) for patients with cirrhotic hypersplenism, we observed a phenomenon of visible hepatic regeneration. This study aims to investigate the potential mechanism of RFA-induced liver regeneration, and the 2-year outcomes of splenic RFA. METHODS: Forty patients who underwent splenic RFA for cirrhotic hypersplenism were followed for 24 months. Before and after RFA procedures, portal hemodynamics and liver and spleen volumes were measured by Doppler ultrasonography and computed tomography volumetry. Liver function tests and blood counts were also determined. RESULTS: The splenic and portal venous flows decreased, but hepatic arterial flow (HAF) increased dramatically after the RFA procedure. Liver volumes at 3 month post-RFA increased compared to the baseline volumes (872 +/- 107 vs. 821 +/- 99 cm(3), P = .031). A correlation was found between maximum absolute values of liver volumes (triangle upliver volumes) and that of HAF (triangle upHAF) in Child-Pugh class A/B patients (r = 0.60; P < .001). Leukocyte and platelet counts, as well as liver function, improved substantially during the 2-year follow-up. Patients with > or = 40% of spleen volume ablated had better improvement of thrombocytopenia. No death or severe complications occurred. CONCLUSIONS: RFA for cirrhotic hypersplenism is safe and efficacious. The increase in HAF as a result of splenic RFA may improve liver function and induce liver regeneration in cirrhotics, but further studies are necessary to clarify the underlying mechanisms.

Pyranine-induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridine) and pH-triggered release of pyranine from the complex micelles.

The pyranine-induced micellization of poly(ethylene glycol)-block-poly(4-vinylpyridine) (PEG114-b-P4VP61) in aqueous solutions and pH-triggered release of pyranine from the complex micelles were studied by dynamic and static light scattering, transmission electron microscopy, 1H NMR spectroscopy, and UV-vis spectroscopy. At pH 2, the ionized pyranine can ionically cross-link the protonated P4VP block and result in well-defined spherical complex micelles with a P4VP/pyranine core surrounded by a PEG corona. The ratio of pyranine to pyridyl units can influence the structure and the properties of the resultant complex micelles. The complex micelles are stable upon dilution and heating but are sensitive to pH changes. pH-triggered release of the incorporated pyranine from the complex micelles demonstrates that the release behavior is pH-tunable and displays good controlled-release characteristics at pH approximately 4.

Evaluation of the role of sympathetic denervation on hepatic function.

It is acknowledged that autonomic nerves play an important role on liver function. Sympathetic nerve is the main component of them. This study is to evaluate the effects of sympathetic denervation of the liver on liver function in the normal and chemically injured liver, and its influence on liver regeneration. Eighty healthy male Wistar rats were divided randomly into four groups: Sham group, carbon tetrachloride group (CCL4), 6-hydroxydopamine group (6-OHDA), and CCL4+6-OHDA group. Chemical denervation model was made by injection of 6-OHDA (2ml, 100mg/l) through the mesenteric vein of jejunum loop. Acute liver injury model was established by using CCL4. Blood chemistry, ATP, arterial ketone body ratio (AKBR) and indocyanine green (ICG(15)) were measured in each group after administration of sympathetic denervation or/and acute liver injury. Liver regeneration was assessed with hepatic mass index (HMI), rate of liver regeneration (RLR), mitotic index (MI) and the rates of DNA synthesis under sympathetic denervation. Chemical denervation resulted in significant changes of liver function tests under acute liver injury, and had beneficial effects on protein anabolism, metabolism of bilirubin and energy, and ICG excretion, meanwhile, alleviated low potassium in serum. However, sympathetic denervation only had no effects on liver function tests. It decreased significantly in sympathetic denervation group for HMI, RLR, MI and the rate of DNA synthesis with 3H-TdR (P<0.01). It is concluded that sympathetic denervation can alleviate liver injury by CCL4, impair liver regeneration, but has no effects on liver function tests under normal.

[Experimental study on tolerance time limits from warm ischemia to cold preservation of liver grafts].

OBJECTIVE: To investigate the tolerance time limits from warm ischemia to cold preservation of liver grafts. METHODS: Orthotopic liver transplantations (OLTs) were performed on Bama miniature swine. Morphological and functional changes of the liver grafts and biliary tracts after 10 minutes of warm ischemia followed by different durations of cold preservation and its reversibility were investigated. RESULTS: When the grafts were subjected to 10 minutes of warm ischemia followed by less than 16 hours of cold preservation, all animals could survive 1 week and there was no animal death from biliary necrosis. However, when the cold preservation time exceeded 16 hours, the incidence of biliary necrosis was significantly increased (P<0.05), and recipient death from bile leaks occurred. With further prolongation of the cold preservation time, primary graft nonfunction and intraoperative or early postoperative deaths occurred and the living animals all developed biliary necrosis. When compared with the less than 16 hours cold preservation group, the morphological scores and apoptosis index of the epithelial cells of bile ducts in grafts after reperfusion were significantly elevated in the more than 16 hours cold preservation group (P<0.05) and the activity of Na+-K+-ATPase and Ca2+-ATPase of bile ducts in grafts were also significantly reduced (P<0.05). Liver function tests showed that the recoveries of AST, AST, GGT and ALP were quicker in the 16 hours cold preservation group then those over 16 hour preservation ones. Correlation analysis revealed that the incidence of biliary necrosis was significantly correlated with the morphological score (r = 0.972) and with the apoptosis index of the epithelial cells of bile ducts in grafts after reperfusion (r = 0.931) and also correlated negatively (P<0.01) with the activity of Na+-K+-ATPase (r = -0.973) and Ca2+-ATPase (r = -0.973). CONCLUSIONS: It is concluded that with 10 minutes of warm ischemia, cold preservation of the grafts should not be longer than 16 hours in order to avoid early biliary necrosis, and the corresponding tolerance time limit of the livers to the cold preservation was less than 20 hours.