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A method for the design, construction, and assembly of modular, polymer-based, microfluidic devices using simple micro-assembly technology was demonstrated to build an integrated fluidic system consisting of vertically stacked modules for carrying out multi-step molecular assays. As an example of the utility of the modular system, point mutation detection using the ligase detection reaction (LDR) following amplification by the polymerase chain reaction (PCR) was carried out. Fluid interconnects and standoffs ensured that temperatures in the vertically stacked reactors were within ± 0.2 C° at the center of the temperature zones and ± 1.1 C° overall. The vertical spacing between modules was confirmed using finite element models (ANSYS, Inc., Canonsburg, PA) to simulate the steady-state temperature distribution for the assembly. Passive alignment structures, including a hemispherical pin-in-hole, a hemispherical pin-in-slot, and a plate-plate lap joint, were developed using screw theory to enable accurate exactly constrained assembly of the microfluidic reactors, cover sheets, and fluid interconnects to facilitate the modular approach. The mean mismatch between the centers of adjacent through holes was 64 ± 7.7 μm, significantly reducing the dead volume necessary to accommodate manufacturing variation. The microfluidic components were easily assembled by hand and the assembly of several different configurations of microfluidic modules for executing the assay was evaluated. Temperatures were measured in the desired range in each reactor. The biochemical performance was comparable to that obtained with benchtop instruments, but took less than 45 min to execute, half the time.

One of the long-standing problems for nanoparticle-based liquid-repellent coatings is their poor adhesion to substrates. For polymers with low glass transition temperatures, it is highly desirable to have a low temperature coating strategy to fabricate robust superhydrophobic films. Here, we report a facile method for fabricating robust, transparent, superhydrophobic films on polymer substrates. A mixture of silica particles and silica-based oligomers was spin coated on polymer substrates, followed by oxygen plasma treatment and vapor deposition of 1 H,1 H,2 H,2 H-Perfluorodecyltriethoxysilan (FDTS). The resulting superhydrophobic surface has a static contact angle of 160° and contact angle hysteresis less than 5°. This is a practical solution for improving the adhesion of superhydrophobic films on polymer substrates under ambient conditions.

This research evaluated the use of a milling machine to texture pavement surfaces and its effect on skid improvement. Texturing tests with different milling drums, forward speeds and cutting depths were conducted on 31 asphalt pavement sections across Texas. Macrotexture and friction were measured before the milling and 3, 6, 12, and 18 months after the milling. The results show that sections milled with fine drums exhibited a higher skid resistance and macrotexture after milling. The test results also indicate that the forward milling speed is positively associated with both skid resistance and macrotexture. In other words, higher milling speeds tend to produce surfaces with higher skid resistance and macrotexture. The data suggests that milling operations on average provide a service life of about 12 months on seal coats, whereas milling on HMA sections extends the service life beyond 18 months.

Bedside ultrasound is an extremely valuable and rapidly accessible diagnostic and therapeutic modality in potentially life- and limb-threatening situations in the emergency department. In this report, the authors discuss the role of ultrasound in quick assessment of pathologic conditions and its use to aid in diagnostic and therapeutic interventions.

Objective Aortic annular erosion is a serious complication of aortic valve endocarditis or previous aortic valve replacement without endocarditis, and its surgical management is challenging. We present the early and midterm results of a technique for left ventricular outflow tract and aortic root reconstruction with a polyester tube graft and translocation of the aortic valve and coronary arteries. Methods A polyester tube graft is placed into the left ventricle and sutured to the left ventricular outflow tract below the area of erosion. The graft is then everted and sutured to a composite graft. Interposition polyester grafts from the coronary arteries are attached to the composite graft above the valve. This technique has been used in 12 cases. All but 1 patient had previously undergone aortic root or aortic valve replacement, and 4 had endocarditis of prosthetic (n = 2) or aortic allograft (n = 2) valves. Results There were no in-hospital deaths. There was 1 early death from pulmonary embolism at 1 postoperative month and 2 late deaths at 15 and 64 postoperative months, both resulting from heart failure. The remaining 9 patients are alive at 3 to 132 postoperative months. Actuarial 5-year survival is 75%. Conclusions Left ventricular outflow tract reconstruction with translocation of the aortic valve and coronary arteries for annular erosion is a useful technique that safely excludes the area of annular erosion and eliminates left ventricular outflow tract obstruction. The procedure can be safely performed with satisfactory early outcomes and 5-year survival.

Arrays of nanowires and nanotubes of bismuth–tellurium (Bi–Te) were fabricated by electrodeposition techniques. Scanning electron microscopy was employed to characterize the morphology of the fabricated BiTe nanowires and nanotubes. The fabricated BiTe nanowire and nanotube arrays are shown to be polycrystalline with no preferred orientation. Wavelength dispersive spectroscopy analysis shows that either p-type (Bi rich) or n-type (Te rich) nanowires or nanotubes can be obtained by changing the electrodeposition potentials. The lamellar thickness of the nanowires and nanotube crystallites were determined using the Scherrer equation and found to be ∼17–24 nm. The Seebeck coefficient measurements at room temperature obtained for the nanowires and nanotubes deposited at −400 mV were +11.5 and +17 μV K−1, respectively, whereas those obtained at −65 mV were −48 and −63 μV K−1, respectively. The electrical resistance measurements indicated that the resistance of the nanowires and nanotubes decreased with increasing temperature, suggesting that these nanostructures behave like semiconductors.

There are many studies of the Pediatric Symptom Checklist (PSC), but none has followed a naturalistic sample longitudinally. We aimed to examine persistence and change in PSC scores over time in children seen in an ambulatory pediatric setting.The sample of 1033 patients was PSC screened at 2 consecutive preventive care visits (10 to 18 months apart) in 2 pediatric clinics. Longitudinal analyses were conducted to assess predictors of change in PSC category and score.Approximately 30% of the initially screened population did not return for preventive pediatric care. Those who did not return were significantly more likely to have positive PSC scores than those who returned (8% compared with 4.3%, P.01). PSC scores were highly stable at visit 2 for those who initially scored negative, but they fluctuated more for those who initially scored positive. After controlling for sociodemographic variables and counseling at either visit, referral at visit 1 (P.0001) predicted changes in mean PSC scores at visit 2. On average, PSC score decreased 3.2 points among those referred at visit 1 but increased 1.6 points in nonreferred children.This is the first study to document the stability and change in PSC scores in a sample of ambulatory pediatric patients. The statistically significant association between pediatrician referral and improved PSC scores provides evidence for the value of referral in primary care, although the study did not examine the relationship between PSC screening and referral. The high rate of positive scores in children who did not return for follow-up suggests the need for alternative strategies for this population.

Background We evaluated a one-stage technique for extensive replacement of the thoracic aorta in patients with chronic aortic dissection. Methods Fifty-one patients with chronic expanding thoracic aortic dissections (48 type A, 3 type B with proximal extension) were treated with a single procedure using a bilateral anterior thoracotomy, hypothermic circulatory arrest, and reperfusion of the arch vessels first to minimize brain ischemia. Forty-six patients had previous operations: for acute type A aortic dissection (n = 36), aortic valve disease (n = 6), or coronary artery disease (n = 4). The ascending aorta and entire arch were replaced in all patients combined with varying lengths of the descending aorta. Results Hospital mortality was 3.9% (2 patients). Five patients (10%) required reoperation for bleeding. Two patients were discharged on ventilatory support and 2 on dialysis. No patient sustained a stroke, and paraplegia developed in one. The 5- and 7-year survival rates were 79% and 68%. Freedom from reoperation on the thoracic or abdominal aorta was 92% at 5 and 7 years postoperatively. Serial tomograms have documented substantial enlargement of the residual dissected aorta in only 2 patients (reoperated). Conclusions The technique is a safe and suitable alternative to the two-stage (elephant trunk technique) and hybrid procedures for treatment of chronic dissection with aneurysm of the thoracic aorta. It eliminates the risk of rupture in the interval between staged procedures and the risks associated with a second thoracic aortic procedure, and is associated with a low rate of reoperation on the remaining aorta.

Our laboratory has previously reported a nonmyelosuppressive preparative regimen for hematopoietic cell transplantation that leads to mixed chimerism and allograft tolerance in miniature swine across minor and major histocompatibility disparities. Stable chimerism persisted in most of these animals but was restricted to T cells and confined to peripheral blood. Because of the importance of myeloid and erythroid progenitors for the treatment of hematologic disorders, the objective of this study was to assess whether such cells existed in the bone marrow of these lymphoid chimeras as an indication of functional engraftment. Colony-formation assays were performed on donor inocula before infusion and on bone marrow cells harvested from the transplant recipients. Donor-origin myeloid/erythroid progenitor colonies were detected in bone marrow from 6 of 7 lymphoid chimeric recipients. A delayed donor leukocyte infusion successfully converted a stable lymphoid chimera to full multilineage chimerism within 2 weeks. Donor-origin myeloid/erythroid progenitors could be detected in the bone marrow of a host-matched recipient after myeloablation and adoptive transfer of mobilized cells from one of the engrafted lymphoid chimeras. These data suggest that even when only lymphoid chimerism is readily detected by flow cytometry, dormant myeloid/erythroid progenitors can exist and subsequent conversion to full donor chimerism can be achieved. The ability to establish multilineage engraftment and chimerism without significant toxicity may have important clinical implications for the management of nonmalignant hematopoietic disorders and hematologic malignancies.

Measurement of three-dimensional, skeletal kinematics is important for clinicians and engineers alike. Most in vivo motion data are acquired using skin-mounted markers or marker arrays. Experiments were carried out to quantitatively evaluate the validity of using skin-mounted markers to measure the three-dimensional kinematics of the underlying bone. Kinematic data for marker arrays mounted on skeletal pins screwed directly into the bone were compared with data for markers, and arrays of markers, mounted on the skin. Findings included: (1) Task-dependent soft tissue motion relative to the underlying bone of up to twenty millimeters was measured; (2) The accuracy of segmental rigid body velocity estimates was inadequate for determining instantaneous helical axis (IHA) parameters; (3) Power spectra for skin- and pin-mounted arrays cover similar frequency bands and there was no evidence of a distinct, frequency domain soft tissue artifact; (4) Joint angles calculated from the relative rotation of skin-mounted arrays had significant differences compared to the expected values due to soft tissue effects; and (5) Skin-mounted marker data exhibited a transient response to heel strike in gait, but for low-mass markers the transient was well-damped and could be removed with optimal smoothing.

Bentall's technique for repair of annuloaortic ectasia has been associated with postoperative bleeding and with false aneurysms at the anastomotic site between the coronary orifices and valve-containing graft. To reduce the incidence of these complications, we modified the Bentall procedure, using a simplified technique to implant the graft and to create a fistula between the closed perigraft space and right atrium to control bleeding. A continuous suture of monofilament polypropylene was used to implant the prosthetic valve ring and to anastomose the coronary orifices to the Dacron fabric. In some instances, a brief period of hypothermic circulatory arrest was needed to perform the distal aortic anastomosis. Among 562 patients undergoing operation for aneurysm of the ascending aorta between January 1, 1980, and February 28,1990, 280 underwent graft replacement with a valve-containing composite conduit. Most (82%) had annuloaortic ectasia. In 267, we performed a classic Bentall procedure with direct anastomosis between the coronary orifices and fabric graft. The remaining 13 patients underwent other procedures for coronary connection. Early mortality was 5.0%. Reoperation for bleeding was needed in 13.2% of patients who underwent operation before we used the right atrial fistula technique and in 4.4% after we began to use the technique ( p = 0.044). Actuarial survival was 71% at 5 years and 65% at 7 years. For hospital survivors, it was 76% at 5 years and 70% at 7 years. During follow-up, only 9 patients have required reoperation. A false aneurysm at the coronary anastomosis, which was associated with prosthetic valve endocarditis, developed in 1 patient. No permanent fistulas have developed. Thus, by using simplified methods to implant the graft and to control postoperative bleeding, the Bentall technique can be performed successfully with excellent early and late results.

From 1964 to 1989, we performed operations on 133 patients with cardiac tumors. There were 58 male and 75 female patients ranging in age from three days to 81 years; 101 were adults, and 32 were children (less than 12 years of age). Primary tumors (102 benign and 12 malignant) were found in 114 patients and metastatic tumors in 19. Symptoms included congestive heart failure, arrhythmias, emboli, and chest pain. Diagnosis was accomplished through angiography, echocardiography, computed tomography, and magnetic resonance imaging. Operative treatment encompassed techniques ranging from biopsy to complete excision (including hypothermic circulatory arrest and cardiac autotransplantation) depending on the site of disease and the extent of involvement. Overall operative survival was 91%. Twelve patients died early (within 30 days of operation), and follow-up was obtained for 110 (90.9%) of the remaining 121 survivors (total patient-years of follow-up, 572.8; mean follow-up, 5.2 years). Of the 20 patients who died late, 15 had malignant disease. Operative survival for patients with primary cardiac malignancies and for those with metastatic disease was 83% and 68.4%, respectively, with 3 and 5 patients, respectively, still living. We advocate an aggressive surgical approach, especially in patients with benign tumors, who can expect an excellent outcome. For patients with malignant or metastatic disease, palliation and cure are also possible if aggressive surgical actions are taken.

stabilization of the long-segmental tracheobronchomalacia has been described. This report demonstrates that this concept is effective for carinal stabilization. A recent study of 40 children, 11 of whom had left PA sling, identified preoperative mechanical ventilatory support and duration of CPB to be significant risk factors for prolonged postoperative ventilatory support. Repair of PA sling complex and other cardiovascular anomalies increases the complexity of surgery and duration of CPB, thus exposing patients to a higher risk of prolonged postoperative ventilatory support. Excessive endotracheal granulation at the site of mechanical irritation by the endotracheal tube often develops in patients with PA sling complex and tracheomalacia, who require prolonged ventilatory support. External stabilization of the carina permitted an uneventful and early extubation in our patient despite prolonged CPB. Covering the trachea with the pericardial flap after tracheoplasty, as previously described, was helpful in our patient to reinforce the tracheal anastomotic seal, to prevent erosion of the polytetrafluoroethylene (GoreTex) rings into the blood vessels, and to enable safer subsequent bronchoscopic interventions. Potential long-term

During a 27-year-period, 663 adults of the Jehovah's Witness faith underwent open heart procedures at the Texas Heart Institute. To determine the effect of recent changes in operative techniques and in the patient population itself on early mortality, we reevaluated the surgical outcome in this special group of patients. We reviewed the charts of 88 consecutive Jehovah's Witness patients who had an open heart operation between January 1986 and March 1989 and compared demographic variables in this group with those of 575 patients who underwent operation between May 1963 and January 1986. In our recent series, patients were older (mean age, 61 years versus 54 years), and 16% were seen for repeat procedures. Early mortality (less than or equal to 30 days postoperatively) was lower in the recent series than in the earlier series (7.0% versus 10.7%), but the difference between the groups was not statistically significant. We identified several important factors associated with an increased risk of early death in the recent group of patients. These factors included repeat cardiac operations (p less than 0.01), especially for valvar dysfunction, severe left ventricular dysfunction (defined as an ejection fraction less than 0.35) (p less than 0.01), and a hemoglobin level lower than 80 g/L (8 g/dL) (p less than 0.01) on postoperative day 1. Although blood loss remains the leading cause of death in these patients, cardiac operations can be performed with an acceptable mortality.

Between June 1981 and June 1988, we placed pleuroperitoneal shunts in 16 patients for the management of refractory chylothorax on the Pediatric Surgical Service, University of Virginia. The cause of the chylothorax was caval thrombosis from central venous catheters in 5 patients, idiopathic in 3, and mediastinal lymphangioma in 2, and in 6, it developed after a cardiac procedure. Chylothorax in each patient was unresponsive to thoracentesis, tube thoracostomy, and dietary manipulations. A Denver double-valved shunt system is currently employed and is implanted using general anesthesia. Manual pumping is required postoperatively for several months. Twelve (75%) of the 16 patients had excellent results with complete elimination of the chylothorax and resolution of symptoms. In 10 of these 12, the shunt has been removed. Four had an unsatisfactory result: 3 had inferior vena cava hypertension, and 3 were low-birth-weight premature infants. Four patients seen early in this series required revision of the position of the pleural catheter, with successful drainage in each instance. Pleuroperitoneal shunting is a safe, simple, and effective treatment of chylothorax in infants and children. In view of our success in treating chylothorax with these shunts, we recommend early shunting before the development of nutritional or immunological depletion.

Cardiac surgical emergencies are broken down into three categories: cardiac trauma, aortic dissection, and surgery for acute myocardial infarctions. Emphasis is given to describing the presentation of patients with such problems, and to the salient aspects of the clinical strategies for managing each problem. An important goal of each section is focusing the critical care physician on the early recognition of cardiac surgical emergencies and providing him with some rationale for instituting an expeditious plan of therapy.