A model of flow and surfactant transport in an oscillatory alveolus partially filled with liquid

The flow and transport in an alveolus are of fundamental importance to partial liquid ventilation, surfactant transport, pulmonary drug administration, cell-cell signaling pathways, and gene therapy. We model the system in which an alveolus is partially filled with liquid in the presence of surfactants. By assuming a circular interface due to sufficiently strong surface tension and small surfactant activity, we combine semianalytical and numerical techniques to solve the Stokes flow and the surfactant transport equations. In the absence of surfactants, there is no steady streaming because of reversibility of Stokes flow. The presence of surfactants, however, induces a nontrivial cycle-averaged surfactant concentration gradient along the interface that generates steady streaming. The steady streaming patterns (e.g., number of vortices) particularly depend on the ratio of inspiration to expiration periods (I:EI:E ratio) and the sorption parameter KK. For an insoluble surfactant, a single vortex is formed when the I:EI:E ratio is either smaller or larger than 1:1, but the recirculations have opposite directions in the two cases. A soluble surfactant can lead to more complex flow patterns such as three vortices or saddle-point flow structures. The estimated unsteady velocity is 10−3 cm/s10−3cm∕s, and the corresponding Péclet number for transporting respiratory gas is O(1)O(1). For a cell-cell signaling molecule such as surfactant-associated protein-A for regulating surfactant secretion, the Péclet number could be O(10)O(10) or higher. Convection is either comparable to or more dominant than diffusion in these processes. The estimated steady velocity ranges from 10−6 to 10−4 cm/s10−6to10−4cm∕s, depending on I:EI:E and KK, and the corresponding steady Péclet number is between 10−8/Dm10−8∕Dm and 10−6/Dm10−6∕Dm (DmDm is the molecular diffusivity with units of cm2/scm2∕s). Therefore, for Dm ⩽ 10−8 cm2/sDm⩽10−8cm2∕s, the convective transport dominates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87925/2/031510_1.pd

Robotic Repair of Congenital Paraesophageal Hiatal Hernia

Abstract Congenital paraesophageal hiatal hernias are rare and can be associated with gastric incarceration, volvulus, mucosal ulceration, and anemia. Primary repair of the hernia and fundoplication are recommended. In this paper, we report a case of a 3-year-old child with abdominal pain who was noted to have a paraesophageal hiatal hernia with partial gastric volvulus. A 5 mm robot platform was utilized to facilitate hernia sac dissection, hiatal repair, and fundoplication.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63210/1/lap.2008.0185.pd

Regulating Assisted Reproduction in Canada, Switzerland, and the USA: Comparing the Judicialization of Policy-making

This article analyses the extent to which courts shape policies for assisted reproduction. While the USA is considered to be the most litigious country, Canada has observed a growing involvement of the courts from the 1980’s onward, and Switzerland is characterized by a modest degree of judicialization. Based on national patterns, we would expect litigation and court impact to vary across these three countries. As this paper demonstrates, policy-process specific variables such as the structure of policy conflicts, the novelty of regulation, self-regulation by key stakeholders, and the policies in place better explain the variation in the judicialization of policy-making

Understanding the Operative Experience of the Practicing Pediatric Surgeon: Implications for Training and Maintaining Competency

Importance The number of practicing pediatric surgeons has increased rapidly in the past 4 decades, without a significant increase in the incidence of rare diseases specific to the field. Maintenance of competency in the index procedures for these rare diseases is essential to the future of the profession. Objective To describe the demographic characteristics and operative experiences of practicing pediatric surgeons using Pediatric Surgery Board recertification case log data. Design, Setting, and Participants We performed a retrospective review of 5 years of pediatric surgery certification renewal applications submitted to the Pediatric Surgery Board between 2009 and 2013. A surgeon’s location was defined by population as urban, large rural, small rural, or isolated. Case log data were examined to determine case volume by category and type of procedures. Surgeons were categorized according to recertification at 10, 20, or 30 years. Main Outcome and Measure Number of index cases during the preceding year. Results Of 308 recertifying pediatric surgeons, 249 (80.8%) were men, and 143 (46.4%) were 46 to 55 years of age. Most of the pediatric surgeons (304 of 308 [98.7%]) practiced in urban areas (ie, with a population >50 000 people). All recertifying applicants were clinically active. An appendectomy was the most commonly performed procedure (with a mean [SD] number of 49.3 [35.0] procedures per year), nonoperative trauma management came in second (with 20.0 [33.0] procedures per year), and inguinal hernia repair for children younger than 6 months of age came in third (with 14.7 [13.8] procedures per year). In 6 of 10 “rare” pediatric surgery cases, the mean number of procedures was less than 2. Of 308 surgeons, 193 (62.7%) had performed a neuroblastoma resection, 170 (55.2%) a kidney tumor resection, and 123 (39.9%) an operation to treat biliary atresia or choledochal cyst in the preceding year. Laparoscopy was more frequently performed in the 10-year recertification group for Nissen fundoplication, appendectomy, splenectomy, gastrostomy/jejunostomy, orchidopexy, and cholecystectomy (P < .05) but not lung resection (P = .70). It was more frequently used by surgeons recertifying in the 10-year group (used in 11 375 of 14 456 procedures [78.7%]) than by surgeons recertifying in the 20-year (used in 6214 of 8712 procedures [71.3%]) or 30-year group (used in 2022 of 3805 procedures [53.1%]). Conclusions and Relevance Practicing pediatric surgeons receive limited exposure to index cases after training. With regard to maintaining competency in an era in which health care outcomes have become increasingly important, these results are concerning

Effect of Perflubron-induced lung growth on pulmonary vascular remodeling in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) involves lung hypoplasia and pulmonary hypertension (PH). Post-natal Perflubron ventilation induces lung growth. This phenomenon is called Perflubon-induced lung growth (PILG). However, it does not appear to ameliorate PH in CDH. We aim to determine the effect of PILG on pulmonary vascular remodeling in neonates with CDH and PH requiring extracorporeal membrane oxygenation (ECMO)

Thoracoscopic Repair of Congenital Diaphragmatic Hernia in Neonates: Lessons Learned

Abstract Purpose: We sought to characterize our recent experience with thoracoscopic congenital diaphragmatic hernia (CDH) repair and identify patient selection factors. Methods: We reviewed the medical records of full-term neonatal (<1 month of age) patients who underwent thoracoscopic CDH repair between 2004 and 2008 (n=15). We obtained data on prenatal diagnosis, characteristics of the CDH and repair, complications, and outcome. Results: All patients were stabilized preoperatively and underwent repair at an average of 5.7+/-1.3 days. Six patients were prenatally diagnosed, including the 5 inborn. Thirteen defects were left-sided. All were intubated shortly after birth and 2 required extracorporeal membrane oxygenation (ECMO). Twelve of 15 (80%) patients underwent successful thoracoscopic primary repair, including 1 of the patients who required ECMO prior to repair. Conversion to open repair occurred in 3 of 15 (20%) patients because of the need for patch closure or intraoperative instability. Among those converted to open, all had left-sided CDH defects and 3 had stomach herniation (of 5 such patients). Patients spent an average of 6.9+/-1.0 days on the ventilator following repair. The average time until full-enteral feeding was 16.7+/-2.25 days, and average length of hospital stay was 23.8+/-2.73 days. All patients survived to discharge, and average length of follow-up was 15.3+/-3.6 months. Conclusions: Thoracoscopic repair of CDH is a safe, effective strategy in patients who have undergone prior stabilization. Stomach herniation is associated with, but does not categorically predict, conversion to open repair. ECMO use prior to repair should not be an absolute contraindication to thoracoscopic repair.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78119/1/lap.2009.0129.pd

Activism and Legitimation in Israel's Jurisprudence of Occupation

Colonial law need not exclude the colonized in order to subordinate them, and ‘activist’ courts can advance the effect of subordination no less than ‘passive’ courts. As a case study, this article examines the jurisprudential legacy of the Israeli Supreme Court in the context of the prolonged Israeli occupation of Palestine. Applying insights from legal realist, law and society, and critical legal studies scholarship, the article questions the utility of using the activist and passive labels. It illustrates how the Israeli activist court, through multiple legal and discursive moves, has advanced and legitimated the colonization of Palestine; that the court is aware of its role; and that arguments that focus on the court’s informal role do not mitigate this legitimating effect. Unlike other scholars, the article shows that the Israeli court’s role—by extending the power of judicial review to the military’s actions in the occupied areas—is neither novel nor unique or benevolent, as the British colonization of India and the US colonization of Puerto Rico show

Axoplasmic flow of tritiated proline in the corticospinal tract of the rat

The rates of axoplasmic transport were studied in the corticospinal tract of the rat by injecting tritiated proline into the sensory-motor cortex and subsequently analyzing the distribution of incorporated label in the spinal cord at intervals after injection. A mathematical model of the anatomy of the corticospinal tract was developed and used in analysis of the data. The rate of a fast component was calculated to be 240–420 mm per day, which is comparable with rates of fast components in the peripheral nervous system (PNS), but considerably greater than rates in other tracts in the central nervous system. A slow component was calculated to have a transport rate of 3–8 mm per day which is greater than rates found either in the CNS or PNS. This higher rate may be related to the greater length of the corticospinal tract as compared to other CNS tracts studied.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47674/1/441_2004_Article_BF00249212.pd