Breathing pattern of neonates during nonnutritive sucking

Alteration of the breathing pattern seen during oral feeding has been attributed to the behavioral activity of sucking, repeated swallowing, and laryngeal chemoreceptor stimulation. Because it preserves the behavioral activity of sucking but eliminates the laryngeal chemoreceptor stimulation and repeated swallowing that occurs during nutritive sucking, the effects of nonnutritive sucking was evaluated in 19 term infants. The suck-pause pattern seen during nonnutritive sucking is similar to that of nutritive sucking. None of the variables measured (inspiratory duration, expiratory duration, breathing frequency, and tidal volume) were significantly altered during the overall period of nonnutritive sucking when compared with previously obtained control values. These results suggest that the alteration of breathing pattern observed during oral feeding cannot be accounted for by the behavioral activity of sucking per se. However, when the sucking phases of the nonnutritive period were compared with the intervening pauses, a reduction in the expiratory duration (P less than 0.05) and a reduction in tidal volume (P less than 0.05) were observed. Thus, the breathing pattern of human neonates is indeed altered during the sucking phase of the nonnutritive period; pressure changes associated with sucking may account for this alteration.     

Sculpting of an erodible body by flowing water

Erosion by flowing fluids carves striking landforms on Earth and also provides important clues to the past and present environments of other worlds. In these processes, solid boundaries both influence and are shaped by the surrounding fluid, but the emergence of morphology as a result of this interaction is not well understood. We study the coevolution of shape and flow in the context of erodible bodies molded from clay and immersed in a fast, unidirectional water flow. Although commonly viewed as a smoothing process, we find that erosion sculpts pointed and cornerlike features that persist as the solid shrinks. We explain these observations using flow visualization and a fluid mechanical model in which the surface shear stress dictates the rate of material removal. Experiments and simulations show that this interaction ultimately leads to self-similarly receding boundaries and a unique front surface characterized by nearly uniform shear stress. This tendency toward conformity of stress offers a principle for understanding erosion in more complex geometries and flows, such as those present in nature.     

Crosstalk between the lipopolysaccharide and phospholipid pathways during outer membrane biogenesis in Escherichia coli

The outer membrane of gram-negative bacteria is composed of phospholipids in the inner leaflet and lipopolysaccharides (LPS) in the outer leaflet. LPS is an endotoxin that elicits a strong immune response from humans, and its biosynthesis is in part regulated via degradation of LpxC (EC 3.5.1.108) and WaaA (EC 2.4.99.12/13) enzymes by the protease FtsH (EC 3.4.24.-). Because the synthetic pathways for both molecules are complex, in addition to being produced in strict ratios, we developed a computational model to interrogate the regulatory mechanisms involved. Our model findings indicate that the catalytic activity of LpxK (EC 2.7.1.130) appears to be dependent on the concentration of unsaturated fatty acids. This is biologically important because it assists in maintaining LPS/phospholipids homeostasis. Further crosstalk between the phospholipid and LPS biosynthetic pathways was revealed by experimental observations that LpxC is additionally regulated by an unidentified protease whose activity is independent of lipid A disaccharide concentration (the feedback source for FtsH-mediated LpxC regulation) but could be induced in vitro by palmitic acid. Further experimental analysis provided evidence on the rationale for WaaA regulation. Overexpression of waaA resulted in increased levels of 3-deoxy-d-manno-oct-2-ulosonic acid (Kdo) sugar in membrane extracts, whereas Kdo and heptose levels were not elevated in LPS. This implies that uncontrolled production of WaaA does not increase the LPS production rate but rather reglycosylates lipid A precursors. Overall, the findings of this work provide previously unidentified insights into the complex biogenesis of the Escherichia coli outer membrane.The outer membrane of gram-negative bacteria is decorated with a potent endotoxin (called lipid A), which plays a significant role in bacterial pathogenicity and immune evasion (1). It also acts as a physical barrier protecting the cell from chemical attack and represents a significant obstacle for the effective delivery of numerous antimicrobial agents (2, 3). The outer membrane is composed of phospholipids in the inner leaflet and lipopolysaccharides (LPS) in the outer leaflet (4). Phospholipids consist of a glycerol molecule, a phosphate group, and two fatty acid moieties (except for cardiolipins) (5) (see reviews (5, 6) and SI Appendix for the biosynthesis and regulation of phospholipids). LPS, on the other hand, contains three distinct components: lipid A, core oligosaccharides, and O-antigen (7, 8). Lipid A is the sole essential component of LPS, and its biosynthesis involves nine enzyme-catalyzed reactions (8). The lipid A pathway has been widely investigated, and we recently produced a pathway model that incorporates all of the known regulatory mechanisms (9). Briefly, the first reaction step catalyzed by LpxA is highly unfavorable, which makes the proceeding enzyme, LpxC, the first committed enzyme (10). LpxC is regulated by the protease FtsH (11, 12), and we recently postulated that the negative feedback signal arises from lipid A disaccharide, the substrate for LpxK (9). Furthermore, FtsH regulates WaaA (formerly called KdtA), an enzyme downstream of LpxC (13). The exact rationale for WaaA regulation remains unknown.A wealth of research exists for either LPS or phospholipids biosynthesis; however, our current understanding on the crosstalk between both pathways is limited at the moment. Because both pathways are synchronized to ensure a proper balance of membrane components (11, 14), studies underpinning the underlying mechanisms would appear valuable. There are a number of experimental findings that indicate the existence of strong links between both biosynthetic pathways (11, 15, 16). Thus, in the context of outer membrane biogenesis, the role involving phospholipids cannot be ignored in the study of LPS regulation. Furthermore, during membrane synthesis, ∼20 million molecules of fatty acids are synthesized in Escherichia coli (8). Yu et al. (17) reconstituted an in vitro steady-state kinetic system of fatty acid biosynthesis using purified enzymes and observed that the maximum fatty acid production rate obtainable was 100 µM/min. This production rate falls far below the amount of fatty acids required by a cell in vivo [if one assumes a cell volume of 6.7 × 10⁻¹⁶ L (18) and a generation time of 30 min (19)]. Therefore, to test the consistency of reported in vitro parameters and investigate the role of the biosynthetic enzymes on fatty acids turnover rate, a “systems” approach is necessary. Similarly, ever since the regulation of WaaA by FtsH was first reported (13), no study has investigated the underlying regulatory mechanism to date. This would also appear important because under wild-type conditions, WaaA catalyzes a step that is required for the endotoxic activity of lipid A (20).In this work, we present a detailed picture of the crosstalk between the LPS and phospholipids biosynthetic machinery. Our work involves a computational kinetic model spanning 81 chemical reactions and involving 90 chemical species. Additionally, we used a series of E. coli fatty acid biosynthesis mutants to investigate the effect of substrate flux into the saturated and unsaturated fatty acid pathway on LpxC stability. Our complete model agrees qualitatively with published datasets and with our own experiments. Our results imply that the catalytic activation of LpxK is dependent on unsaturated fatty acids. Furthermore, our experimental investigations have implicated a secondary protease involved in LpxC regulation. Finally, we have provided experimental evidence to explain the rationale for WaaA regulation.     

Hemodynamic study of the effect of the geometric height of leaflets on the performance of the aortic valve under aortic valve reconstruction

BackgroundAlthough aortic valve reconstruction has become an alternative treatment for aortic valve disease, the design of the geometric parameters of the reconstructed leaflet still mainly depends on the experience of doctors. The present study investigates the effects of the height of the leaflets on the performance and biomechanical states of the reconstructed aortic valve.MethodsThis numerical study was carried out using the finite element approach and the lattice Boltzmann method. The dynamic and biomechanical characteristics of the leaflets were evaluated by using the finite element approach, while the blood flow in the aortic sinus was evaluated by applying the lattice Boltzmann method. Three types of leaflets with different heights were designed. Then the dynamic characteristics, stress distribution, and effective orifice area (EOA) of the aortic valve and flow pattern were calculated as the indicators.ResultsThe results demonstrated that the height of the leaflets could indeed regulate the performance and the biomechanical states of the aortic valve. The rapid valve opening times of the 3 types of leaflets gradually reduced along with the decrease of the height ratio (HR_0.8: 120 ms vs. HR_1.0: 68 ms vs. HR_1.2: 31 ms), while the rapid valve closing times (RVCTs) of the 3 types of leaflets were similar to each other (approximately 75 ms). Moreover, the radial displacement of the leaflet at the fully open time increased along with the decrease of the HR of the leaflets (HR_0.8: 8 mm vs. HR_1.0: 6 mm vs. HR_1.2: 4 mm). In addition, the stress level of the leaflets also increased with the increase of the height of the leaflets (max stress, HR_0.8: 0.5 MPa, vs. HR_1.0: 1.1 MPa, vs. HR_1.2: 1.8 MPa). Similarly, the low velocity region near the ascending aortic wall and the wall shear stress (WSS) level on the ventricular side of the leaflets also increased along with the increase of the HR of the leaflets.ConclusionsIn short, the height of the leaflets mainly affects the opening performance of the reconstructed aortic leaflets. The HR of the reconstructed leaflets for adults should be less than 1.0 to balance the opening and closing performance of aortic leaflets.     

Metagenomic systems biology and metabolic modeling of the human microbiome

The human microbiome is a key contributor to health and development. Yet little is known about the ecological forces that are at play in defining the composition of such host-associated communities. Metagenomics-based studies have uncovered clear patterns of community structure but are often incapable of distinguishing alternative structuring paradigms. In a recent study, we integrated metagenomic analysis with a systems biology approach, using a reverse ecology framework to model numerous human microbiota species and to infer metabolic interactions between species. Comparing predicted interactions with species composition data revealed that the assembly of the human microbiome is dominated at the community level by habitat filtering. Furthermore, we demonstrated that this habitat filtering cannot be accounted for by known host phenotypes or by the metabolic versatility of the various species. Here we provide a summary of our findings and offer a brief perspective on related studies and on future approaches utilizing this metagenomic systems biology framework.     

Functional organization of the yeast proteome by a yeast interactome map

It is hoped that comprehensive mapping of protein physical interactions will facilitate insights regarding both fundamental cell biology processes and the pathology of diseases. To fulfill this hope, good solutions to 2 issues will be essential: (i) how to obtain reliable interaction data in a high-throughput setting and (ii) how to structure interaction data in a meaningful form, amenable to and valuable for further biological research. In this article, we structure an interactome in terms of predicted permanent protein complexes and predicted transient, nongeneric interactions between these complexes. The interactome is generated by means of an associated computational algorithm, from raw high-throughput affinity purification/mass spectrometric interaction data. We apply our technique to the construction of an interactome for Saccharomyces cerevisiae, showing that it yields reliability typical of low-throughput experiments from high-throughput data. We discuss biological insights raised by this interactome including, via homology, a few related to human disease.     

Metagenomic systems biology and metabolic modeling of the human microbiome: From species composition to community assembly rules

The human microbiome is a key contributor to health and development. Yet little is known about the ecological forces that are at play in defining the composition of such host-associated communities. Metagenomics-based studies have uncovered clear patterns of community structure but are often incapable of distinguishing alternative structuring paradigms. In a recent study, we integrated metagenomic analysis with a systems biology approach, using a reverse ecology framework to model numerous human microbiota species and to infer metabolic interactions between species. Comparing predicted interactions with species composition data revealed that the assembly of the human microbiome is dominated at the community level by habitat filtering. Furthermore, we demonstrated that this habitat filtering cannot be accounted for by known host phenotypes or by the metabolic versatility of the various species. Here we provide a summary of our findings and offer a brief perspective on related studies and on future approaches utilizing this metagenomic systems biology framework.     

Human milk microbiota development during lactation and its relation to maternal geographic location and gestational hypertensive status

ABSTRACT

Bacteria in human milk could directly seed the infant intestinal microbiota, while information about how milk microbiota develops during lactation and how geographic location, gestational hypertensive status, and maternal age influence this process is limited. Here, we collected human milk samples from mothers of term infants at the first day, 2 weeks, and 6 weeks postpartum from 117 longitudinally followed-up mothers (age: 28.7 ± 3.6 y) recruited from three cities in China. We found that milk microbial diversity and richness were the highest in colostrum but gradually decreased over lactation. Microbial composition changed across lactation and exhibited more discrete compositional patterns in 2-week and 6-week milk samples compared with colostrum samples. At phylum level, the abundance of Proteobacteria increased during lactation, while Firmicutes showed the opposite trend. At genus level, Staphylococcus, Streptococcus, Acinetobacter, Pseudomonas, and Lactobacillus were predominant in colostrum samples and showed distinct variations across lactation. Maternal geographic location was significantly associated with the milk microbiota development and the abundance of predominant genus. In addition, milk from mothers with gestational prehypertension had a different and less diverse microbial community at genus level in early lactation times, and contained less Lactobacillus in the 2-week milk samples than those from normotensive mothers. Findings of our study outlined the human milk microbial diversity and community development over lactation, and underscored the importance of maternal geographic locations and gestational hypertensive status on milk microbiota, which might have important implications in the establishment of the infant intestinal microbiota via breastfeeding.     

Contrast-enhanced ultrasound for quantitative assessment of portal pressure in canine liver fibrosis

AIM: To explore the feasibility of non-invasive quantitative estimation of portal venous pressure by contrast-enhanced ultrasound (CEUS) in a canine model.METHODS: Liver fibrosis was established in adult canines (Beagles; n = 14) by subcutaneous injection of carbon tetrachloride (CCl₄). CEUS parameters, including the area under the time-intensity curve and intensity at portal/arterial phases (Qp/Qa and Ip/Ia, respectively), were used to quantitatively assess the blood flow ratio of the portal vein/hepatic artery at multiple time points. The free portal venous pressures (FPP) were measured by a multi-channel baroreceptor using a percutaneous approach at baseline and 8, 16, and 24 wk after CCl₄ injections in each canine. Liver biopsies were obtained at the end of 8, 16, and 24 wk from each animal, and the stage of the fibrosis was assessed according to the Metavir scoring system. A Pearson correlation test was performed to compare the FPP with Qp/Qa and Ip/Ia.RESULTS: Pathologic examination of 42 biopsies from the 14 canines at weeks 8, 16, and 24 revealed that liver fibrosis was induced by CCl₄ and represented various stages of liver fibrosis, including F0 (n = 3), F1 (n = 12), F2 (n = 14), F3 (n = 11), and F4 (n = 2). There were significant differences in the measurements of Qp/Qa (19.85 ± 3.30 vs 10.43 ± 1.21, 9.63 ± 1.03, and 8.77 ± 0.96) and Ip/Ia (1.77 ± 0.37 vs 1.03 ± 0.12, 0.83 ± 0.10, and 0.69 ± 0.13) between control and canine fibrosis at 8, 16, and 24 wk, respectively (all P < 0.001). There were statistically significant negative correlations between FPP and Qp/Qa (r = -0.707, P < 0.001), and between FPP and Ip/Ia (r = -0.759, P < 0.001) in the canine fibrosis model. Prediction of elevated FPP based on Qp/Qa and Ip/Ia was highly sensitive, as assessed by the area under the receiver operating curve (0.866 and 0.895, respectively).CONCLUSION: CEUS is a potential method to accurately, but non-invasively, estimate portal venous pressure through measurement of Qp/Qa and Ip/Ia parameters.     

缺碘地区补碘后哺乳期妇女尿碘乳碘及甲状腺功能研究

目的 了解缺碘地区食用合格碘盐的哺乳期妇女产后半年的碘代谢情况。方法 对乳母及婴儿进行随访观察,测定尿碘,乳主甲状腺激素。结果 产妇分娩时尿碘值为１１５．２８￣９１３。．０２μｇ／Ｌ,中位数４２３．５８μｇ／Ｌ;由于围产期低盐饮食;９０％产妇在产后半年内尿碘水平逐渐下降,婴儿尿碘随之变化;但绝大多数乳母和婴儿尿碘处于下沉碘营养水平。乳碘始终处于较高水平,部分立妇的甲状腺激素ＴＴ４水平偏高,提示：产     

原发性高血压患者肾脏B超形态学改变

目的 :探讨原发性高血压 (EH)患者肾脏及肾实质厚度的异常变化与临床的关系。方法 :应用 B超观测40例 EH患者肾脏及肾实质厚度 ,并与正常组对照分析。结果 :EH组肾脏大小与正常组无显著性差异 ,但肾实质厚度较正常组明显变薄 (P<0 .0 0 1 )。EH组患者的肾实质厚度与舒张压、血清肌酐呈负相关。结论 :肾实质变薄的程度表明肾小动脉硬化 ,残存肾单位总数下降     

Laser Melting Deposition Additive Manufacturing of Ti6Al4V Biomedical Alloy: Mesoscopic In-Situ Flow Field Mapping via Computational Fluid Dynamics and Analytical Modelling with Empirical Testing

Laser melting deposition (LMD) has recently gained attention from the industrial sectors due to producing near-net-shape parts and repairing worn-out components. However, LMD remained unexplored concerning the melt pool dynamics and fluid flow analysis. In this study, computational fluid dynamics (CFD) and analytical models have been developed. The concepts of the volume of fluid and discrete element modeling were used for computational fluid dynamics (CFD) simulations. Furthermore, a simplified mathematical model was devised for single-layer deposition with a laser beam attenuation ratio inherent to the LMD process. Both models were validated with the experimental results of Ti6Al4V alloy single track depositions on Ti6Al4V substrate. A close correlation has been found between experiments and modelling with a few deviations. In addition, a mechanism for tracking the melt flow and involved forces was devised. It was simulated that the LMD involves conduction-mode melt flow only due to the coaxial addition of powder particles. In front of the laser beam, the melt pool showed a clockwise vortex, while at the back of the laser spot location, it adopted an anti-clockwise vortex. During printing, a few partially melted particles tried to enter into the molten pool, causing splashing within the melt material. The melting regime, mushy area (solid + liquid mixture) and solidified region were determined after layer deposition. This research gives an in-depth insight into the melt flow dynamics in the context of LMD printing.     

Identification of signature of gene expression in biliary atresia using weighted gene co-expression network analysis

Biliary atresia (BA) is the most common cause of obstructive jaundice during the neonatal period. This study aimed to identify gene expression signature in BA. The datasets were obtained from the Gene Expression Omnibus database. Weighted gene co-expression network analysis identified a critical module associated with BA, whereas Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed the functions of the essential modules. The high-connectivity genes in the most relevant module constructed protein–protein interaction networks via the string website and Cytoscape software. Hub genes screened by lasso regression consisted of a disease classification model using the randomforest method. Receiver operating characteristic curves were used to assess models’ sensitivity and specificity and the model was verified using the internal and external validation sets. Ten gene modules were constructed by WGCNA, of which the brown module had a strong positive correlation with BA, comprising 443 genes. Functional enrichment analysis revealed that module genes were mainly involved in biological processes, such as extracellular matrix organization, cell adhesion, inflammatory response, and the Notch pathway (P < .001), whereas these genes were involved in the metabolic pathways and cell adhesion molecules (P < .001). Thirty-nine high-connectivity genes in the brown module constructed protein-protein interaction networks. keratin 7 (KRT7) and C-X-C motif chemokine ligand 8 (CXCL8) were used to construct a diagnostic model that had an accuracy of 93.6% and the area under the receiver operating curves for the model was 0.93. The study provided insight into the signature of gene expression and possible pathogenesis of BA; furthermore, it identified that the combination of KRT7 and CXCL8 could be a potential diagnostic model for BA.     

Utilization of Intravascular Ultrasound during Carotid Artery Stenting

For patients at high risk for surgery, carotid artery stenting (CAS) is a viable alternative to help reduce risk of stroke for patients with high-grade carotid artery stenosis; however, a higher incidence of perioperative stroke has been observed in patients undergoing stenting compared to those undergoing open surgery. Intravascular ultrasound (IVUS) is commonly used during coronary artery procedures to help evaluate lesions and to guide stent placement. Multiple groups have sought to determine whether IVUS could also be used during CAS. While IVUS has been shown to be both feasible and safe during CAS, there is limited evidence that demonstrates direct improvement in procedural outcomes. Further studies focusing on clinical outcomes should be conducted in order to justify routine use of this technology during CAS.     

Striatal origin of the pathologic beta oscillations in Parkinson's disease

Enhanced oscillations at beta frequencies (8-30 Hz) are a signature neural dynamic pathology in the basal ganglia and cortex of Parkinson's disease patients. The mechanisms underlying these pathological beta oscillations remain elusive. Here, using mathematical models, we find that robust beta oscillations can emerge from inhibitory interactions between striatal medium spiny neurons. The interaction of the synaptic GABAa currents and the intrinsic membrane M-current promotes population oscillations in the beta frequency range. Increased levels of cholinergic drive, a condition relevant to the parkinsonian striatum, lead to enhanced beta oscillations in the striatal model. We show experimentally that direct infusion of the cholinergic agonist carbachol into the striatum, but not into the neighboring cortex, of the awake, normal rodent induces prominent beta frequency oscillations in the local field potential. These results provide evidence for amplification of normal striatal network dynamics as a mechanism responsible for the enhanced beta frequency oscillations in Parkinson's disease.     

Towards Tuning the Mechanical Properties of Three-Dimensional Collagen Scaffolds Using a Coupled Fiber-Matrix Model

Scaffold mechanical properties are essential in regulating the microenvironment of three-dimensional cell culture. A coupled fiber-matrix numerical model was developed in this work for predicting the mechanical response of collagen scaffolds subjected to various levels of non-enzymatic glycation and collagen concentrations. The scaffold was simulated by a Voronoi network embedded in a matrix. The computational model was validated using published experimental data. Results indicate that both non-enzymatic glycation-induced matrix stiffening and fiber network density, as regulated by collagen concentration, influence scaffold behavior. The heterogeneous stress patterns of the scaffold were induced by the interfacial mechanics between the collagen fiber network and the matrix. The knowledge obtained in this work could help to fine-tune the mechanical properties of collagen scaffolds for improved tissue regeneration applications.     

An ultrasound examination of tongue movement during swallowing

Six female adults were studied during the production of four single swallows each, using real-time ultrasound. A pellet was affixed to the tongue at the junction between the (calculated) anterior third and posterior two-thirds of the tongue surface. Direction, rate, and extent of pellet movement were measured and used to create stages of tongue blade movement during swallowing. Pellet movement was then compared to the three stages of hyoid movement (ascent, steady, descent). Anterior-posterior and superior-inferior components of pellet movement were examined and discussed.     

Calcium-based plasticity model explains sensitivity of synaptic changes to spike pattern, rate, and dendritic location

Multiple stimulation protocols have been found to be effective in changing synaptic efficacy by inducing long-term potentiation or depression. In many of those protocols, increases in postsynaptic calcium concentration have been shown to play a crucial role. However, it is still unclear whether and how the dynamics of the postsynaptic calcium alone determine the outcome of synaptic plasticity. Here, we propose a calcium-based model of a synapse in which potentiation and depression are activated above calcium thresholds. We show that this model gives rise to a large diversity of spike timing-dependent plasticity curves, most of which have been observed experimentally in different systems. It accounts quantitatively for plasticity outcomes evoked by protocols involving patterns with variable spike timing and firing rate in hippocampus and neocortex. Furthermore, it allows us to predict that differences in plasticity outcomes in different studies are due to differences in parameters defining the calcium dynamics. The model provides a mechanistic understanding of how various stimulation protocols provoke specific synaptic changes through the dynamics of calcium concentration and thresholds implementing in simplified fashion protein signaling cascades, leading to long-term potentiation and long-term depression. The combination of biophysical realism and analytical tractability makes it the ideal candidate to study plasticity at the synapse, neuron, and network levels.     

Neural correlates of mentalizing-related computations during strategic interactions in humans

Competing successfully against an intelligent adversary requires the ability to mentalize an opponent's state of mind to anticipate his/her future behavior. Although much is known about what brain regions are activated during mentalizing, the question of how this function is implemented has received little attention to date. Here we formulated a computational model describing the capacity to mentalize in games. We scanned human subjects with functional MRI while they participated in a simple two-player strategy game and correlated our model against the functional MRI data. Different model components captured activity in distinct parts of the mentalizing network. While medial prefrontal cortex tracked an individual's expectations given the degree of model-predicted influence, posterior superior temporal sulcus was found to correspond to an influence update signal, capturing the difference between expected and actual influence exerted. These results suggest dissociable contributions of different parts of the mentalizing network to the computations underlying higher-order strategizing in humans.     

Value of intravascular ultrasound in the assessment of coronary pseudostenosis during coronary interventions

Coronary pseudostenosis (PS) are increasingly visualized during coronary interventions. In many patients PS are readily recognized by a characteristic angiographic pattern, but in other cases the diagnosis remains difficult. The value of intravascular ultrasound (IVUS) in the study of PS remains unknown. In this study, IVUS was used to assess the morphologic appearance of the vessel wall in 10 consecutive patients showing images of PS during coronary interventions. Mean age of the group was 60 ± 12 years and two patients were female. IVUS was performed with a motorized pullback system to assess lumen, plaque, and total vessel cross-sectional areas. Measurements were performed both at the site of PS and at the distal reference segment. PS were always located on angled coronary segments. In one patient no lumen narrowing was detected with IVUS at the site of PS. In the remaining nine patients, however, a very localized elliptic-shaped lumen narrowing was demonstrated. As compared with the distal reference segment, coronary lumen (6.3 ± 2.2 vs. 12.7 ± 4.8 mm², P < 0.001) and total vessel area (11.9 ± 3.3 vs. 16.1 ± 6.1 mm², P < 0.05) were smaller at the site of PS. Severe lumen asymmetry was also documented at this site. In addition, a characteristic image of a flattened, three-layered wall, overlying a hypoechogenic space, was visualized in five patients. This unique pattern was considered the correlate of a partial coronary intussusception. PS induced some resistance to the advancement of catheters in two patients and temporary flow impairment in two additional patients. However, in every case, the image of PS disappeared once the guidewire was removed. Thus, at sites with PS, IVUS allows ruling out severe atherosclerosis and coronary dissections. In addition, IVUS also provides important diagnostic clues, including the image of intussusception, for making the correct diagnosis of this benign entity. Cathet. Cardiovasc. Intervent. 46:327–332, 1999. © 1999 Wiley-Liss, Inc.