Elevated Electron Temperature Coincident with Observed Fusion Reactions in a Sheared-Flow-Stabilized Z Pinch.

The sheared-flow-stabilized Z pinch concept has been studied extensively and is able to produce fusion-relevant plasma parameters along with neutron production over several microseconds. We present here elevated electron temperature results spatially and temporally coincident with the plasma neutron source. An optical Thomson scattering apparatus designed for the FuZE device measures temperatures in the range of 1-3 keV on the axis of the device, 20 cm downstream of the nose cone. The 17-fiber system measures the radial profiles of the electron temperature. Scanning the laser time with respect to the neutron pulse time over a series of discharges allows the reconstruction of the T_{e} temporal response, confirming that the electron temperature peaks simultaneously with the neutron output, as well as the pinch current and inductive voltage generated within the plasma. Comparison to spectroscopic ion temperature measurements suggests a plasma in thermal equilibrium. The elevated T_{e} confirms the presence of a plasma assembled on axis, and indicates limited radiative losses, demonstrating a basis for scaling this device toward net gain fusion conditions.

Sustained Neutron Production from a Sheared-Flow Stabilized Z Pinch.

The sheared-flow stabilized Z pinch has demonstrated long-lived plasmas with fusion-relevant parameters. We present the first experimental results demonstrating sustained, quasi-steady-state neutron production from the fusion Z-pinch experiment, operated with a mixture of 20% deuterium/80% hydrogen by pressure. Neutron emissions lasting approximately 5 µs are reproducibly observed with pinch currents of approximately 200 kA during an approximately 16 µs period of plasma quiescence. The average neutron yield is estimated to be (1.25±0.45)×10^{5} neutrons/pulse and scales with the square of the deuterium concentration. Coincident with the neutron signal, plasma temperatures of 1-2 keV and densities of approximately 10^{17} cm^{-3} with 0.3 cm pinch radii are measured with fully integrated diagnostics.

Implementation of extreme ultraviolet spectroscopy on a sheared-flow-stabilized Z pinch.

A diagnostic for extreme ultraviolet spectroscopy was fielded on the sheared-flow-stabilized (SFS) fusion Z-pinch experiment (FuZE-Q) for the first time. The spectrometer collected time-gated plasma emission spectra in the 5-40 nm wavelength (30-250 eV) range for impurity identification, radiative power studies, and for plasma temperature and density measurements. The unique implementation of the diagnostic included fast (10 ns risetime) pulsed high voltage electronics and a multi-stage differential pumping system that allowed the vacuum-coupled spectrometer to collect three independently timed spectra per FuZE-Q shot while also protecting sensitive internal components. Analysis of line emission identifies oxygen (N-, C-, B-, Be-, Li-, and He-like O), peaking in intensity shortly after maximum current (>500 kA). This work provides a foundation for future high energy spectroscopy experiments on SFS Z-pinch devices.

The incidence of spermatic cord structures in inguinal hernia sacs from male children.

Inguinal herniorrhaphy is a common surgical procedure in children. Controversy exists regarding the usefulness of microscopic examination of hernia sacs, and changes in reimbursement schemes have heightened this controversy. We summarize our experience with histologic examination of these specimens to establish benchmarks for the number of spermatic cord structures in inguinal hernia sacs from male children. A 14 1/2 consecutive calendar year review of pathology reports and histologic sections of hernia sacs was conducted at a tertiary care children's hospital. Of 7,314 males (range newborn to 19 years old), 65% had bilateral and 29% had unilateral herniorrhaphy (6% unknown). Seventeen cases contained vas deferens (0.23%); 22 had epididymis (0.30%); and 30 had embryonal rests (0.41%). Either vas deferens or epididymis was found in 0.53% of patients. No cases contained bilateral vas deferens, bilateral epididymis, or vas deferens in one side with epididymis in the contralateral side. Three hernia sacs contained co-existing vas deferens and epididymis. Our study helps to provide surgeons with information for preoperative counseling regarding potential injury to the vas deferens or epididymis. This study provides baseline comparison data for quality improvement programs. We believe that each institution should weigh the costs, risks, and benefits of performing microscopic examinations on hernia sacs, depending on their own experience and data.

Suppurative thrombophlebitis in childhood.

Thrombophlebitis in children is almost always related to intravenous therapy. In most cases the inflammatory reaction is self-limited and resolves when the intravenous catheter or needle is removed. In some cases contamination may result in suppurative thrombophlebitis, a potentially life-threatening complication of intravenous therapy. This report describes two-6-year-old children with suppurative thrombophlebitis that was successfully treated by drainage of periphlebitic abscess and excision of the infected vein. Early recognition and prompt surgical management should reduce morbidity and prevent mortality in these cases.

Unusual manifestations of histoplasmosis in childhood.

Nine previously healthy children were seen with unique, and in several instances, unreported manifestations of acute histoplasmosis. Presenting manifestations included: obstructive airway disease; subacute parotitis; unilateral cervical lymphadenopathy; anterior mediastinal mass-simulating neoplasm; immune hemolytic anemia; a cutaneous lesion with regional lymphadenopathy; mediastinal mass and pericardial effusion; pulmonary infarction; and a symptom complex of cervical lymphadenopathy, CSF pleocytosis, arthritis, and interstitial nephritis. In eight children histoplasmosis was not initially considered, and the correct diagnosis was made only after complex, and sometimes invasive, diagnostic evaluation and considerable delay. All patients recovered fully without antifungal therapy. Reports of uncontrolled trials of new antifungal agents for treatment of histoplasmosis in immunocompetent hosts should be cautiously evaluated.

Surgical treatment of gastroesophageal reflux in children: a combined hospital study of 7467 patients.

OBJECTIVE: To review retrospectively the combined clinical experience with the surgical treatment of persistently symptomatic gastroesophageal reflux (SGER) in childhood from seven large children's surgery centers in the United States. DESIGN: During the past 20 years, 7467 children <18 years of age underwent antireflux operations for SGER at the seven participating hospitals. Fifty-six percent were neurologically normal (NN) and 44% were neurologically impaired (NI). The most frequent diagnostic studies were upper gastrointestinal series (68%), esophageal pH monitoring (54%), gastric emptying study (32%), and esophagoscopy (25%). The age at operation was under 12 months in 40% and 1 to 10 years in 48%. The type of fundoplication was Nissen (64%), Thal (34%), and Toupet (1.5%). A gastric emptying procedure was performed on 11.5% of NN patients and 40% of NI patients. Laparoscopic fundoplication was performed on 2.6% of patients. RESULTS: Good to excellent results were achieved in 95% of NN and 84.6% of NI patients. Major complications occurred in 4.2% of NN and 12.8% of NI patients. The most frequent complications were recurrent reflux attributable to wrap disruption (7.1%), respiratory (4.4%), gas bloat (3.6%), and intestinal obstruction (2.6%). Postoperative death occurred in 0.07% of NN and 0.8% of NI patients. Reoperation was performed in 3.6% of NN and 11.8% of NI patients. The results and complications were similar among the participating hospitals and did not seem related to the type of fundoplication used. CONCLUSION: The excellent results (94% cure) and low morbidity with gastroesophageal fundoplication with or without a gastric emptying procedure from a large combined hospital study indicate that operation should be used early for SGER in NN children and to facilitate enteral feedings and care in NI children.

Acquired tracheal stenosis in infants and children.

Acquired tracheal stenosis in childhood is frequently difficult to manage because of poor healing, infection, and scarring. In a 10-year period, 62 patients (4 weeks to 14 years of age) were treated for acquired tracheal stenosis. The causes of stenosis were endotracheal intubation (44 patients), caustic aspiration (6 patients), recurrent infection (5 patients), bronchoscopic perforation (4 patients), and gastric aspiration (3 patients). The subglottic or upper trachea was involved in 47 patients, mid portion in 8, and distal or carinal area in 7. Fifty children underwent tracheostomy as part of the therapy, and 12 were managed without tracheostomy. Therapy was individualized, frequently sequentially, utilizing rigid or balloon dilatation (20 patients), bronchoscopic electrocoagulation resection (44 patients), steroid injection (48 patients), T tube stent (8 patients), resection with anastomosis (12 patients), cricoid split (3 patients), and rib cartilage graft (12 patients). Most patients required several techniques and repeated procedures to eventually achieve decannulation. Seven patients (11%) died of unrelated causes. Forty-four of 55 surviving patients (80%) are without tracheostomy, although 14 have required continued endotracheal treatment after tracheostomy removal (dilatation, endotracheal resection). This series demonstrates that acquired tracheal stenosis in childhood is a common, difficult problem, but manageable with the use of a variety of techniques. Resection and grafting procedures should be reserved for cases in which less complex modalities fail.

Congenital bronchopulmonary malformations. Diagnostic and therapeutic considerations.

Congenital bronchopulmonary malformations are uncommon but potentially life-threatening anomalies of infants and children. Between 1970 and 1988, 45 patients from birth to 13 years of age (23 boys and 22 girls) underwent evaluation and treatment for bronchopulmonary malformations. Thirty-seven had solitary lesions: bronchogenic cyst (n = 13), cystic adenomatoid malformation (n = 9), congenital lobar emphysema (n = 6), pulmonary sequestration (n = 6), arteriovenous malformation (n = 2), and bronchial atresia (n = 1). Eight additional patients had two simultaneous abnormalities and three patients had congenital diaphragmatic hernias. Twenty-one patients had respiratory symptoms, which were severe in seven. Twelve had pulmonary infection and 10 patients were completely free of symptoms. Plain chest roentgenogram was the only diagnostic imaging performed in 11 patients. Thirteen patients underwent computed tomographic scan, but in only four was it essential for diagnosis. Prenatal ultrasonography in three patients demonstrated cystic adenomatoid malformation in two, with one false negative study. Postnatally, ultrasonography was also useful in establishing the diagnoses of cystic adenomatoid malformation and pulmonary sequestration. Thoracotomy with excision of the lesion by lobectomy or pneumonectomy resulted in survival of 42 patients (93%). Three deaths in neonates were due to pulmonary hypoplasia and hypertension. Two of them had concomitant diaphragmatic hernia; the other had a cystic adenomatoid malformation and died despite the use of postoperative extracorporeal membrane oxygenation. These data demonstrate that congenital bronchopulmonary malformations usually can be diagnosed by plain chest x-ray films. Ancillary studies such as ultrasonography or computed tomography may occasionally be necessary. Combinations of the different types of bronchopulmonary malformations occurred frequently. All lesions, including symptomatic lesions in neonates, can be managed surgically soon after diagnosis.

Extracorporeal membrane oxygenation for postoperative cardiac support in children.

Prolonged circulatory support for cardiac failure has been increasingly successful in adults but has had very limited use in children. From January 1982 to December 1985, 13 children with postoperative cardiac failure refractory to conventional therapy were treated with extracorporeal membrane oxygenation. Ages ranged from 9 days to 17.6 years (mean = 3.8 years); weights ranged from 2.8 to 50 kg (mean = 13.8 kg). Seven patients had obstructive lesions of the right ventricle, such as pulmonary stenosis and tetralogy; the other patients had tricuspid atresia, truncus arteriosus, complete transposition, total anomalous pulmonary venous connection, pericardial tamponade, and a drug reaction after heart transplantation. One patient (nonsurvivor), who could not be separated from cardiopulmonary bypass, required extracorporeal membrane oxygenation in the operating room. In the remaining 12, the interval between operation and the start of extracorporeal membrane oxygenation ranged from 9 to 50 hours (mean = 22.2 hours). Four patients were cannulated through the groin and nine through the chest. Peak flows ranged from 1.05 to 2.74 L/min/m2 (mean 1.92 L/min/m2). Duration of oxygenator support ranged from 12 hours to 9 days (mean = 3.4 days). Seven patients required reexploration for bleeding. Renal insufficiency developed in five patients, four of whom underwent hemodialysis or ultrafiltration during extracorporeal membrane oxygenation. Two patients had evidence of clots in the oxygenator circuit. Seven patients were weaned from extracorporeal membrane oxygenation. Failure to wean from the oxygenator was related to neurologic sequelae of prolonged hypotension before institution of oxygenation in three patients. Mediastinitis developed in three of the seven patients who were weaned. One of these three died in the hospital 74 days after being weaned from the oxygenator. There has been one late death 6 months after oxygenator support was withdrawn. At most recent examination, five children were well, with normal cardiac function 7 months to 4.3 years postoperatively (mean = 32 months). This series suggests that profound cardiac insufficiency in children after cardiac operations can be successfully managed with extracorporeal membrane oxygenation with excellent functional recovery, although major complications are common in this critically ill group of patients.

One-stage resection for massive cervicomediastinal hygroma.

Cervicomediastinal cystic hygroma has long been recognized as a serious cause of respiratory distress in infancy. This report describes the management of ten infants and children with large cervicomediastinal hygromas. Ages ranged from the newborn to 4 years (average 18.4 months). Six were boys and four were girls. Eight presented with respiratory distress. Neck examination, ultrasonography, and chest x-ray examination were usually diagnostic. In four infants the intrathoracic component was initially clinically unsuspected. The neck lesion descends into the chest between the subclavian vein and artery. At operation the mass was dissected off the pericardium; phrenic, vagus, and recurrent laryngeal nerves; esophagus; aortic arch; and subclavian vessels. Complete resection was possible in each case. Nine of ten patients survived. Death occurred in a newborn with bilateral tumor and pulmonary hypoplasia. Three patients developed Horner's syndrome. There were no recurrences (follow-up 9 months to 10 years). These data indicate that a one-stage resection using an inverted hockey stick (sternum-splitting) incision is well tolerated, curative, and superior to other methods of treatment in infants with cervicomediastinal cystic hygroma.

Growth-related gene expression in early cholestatic liver injury.

BACKGROUND: Extrahepatic biliary obstruction initiates cholestasis, bile duct proliferation, periportal fibrosis, and, eventually, lethal biliary cirrhosis. Little is known about the genetic regulation of the cellular proliferation and differentiation that begins with the onset of bile duct obstruction. To focus this and future gene expression studies, we sought to determine the time frame for growth-related gene expression and questioned whether the in vivo expression of the protooncogenes H-ras and c-myc was altered after bile duct obstruction. METHODS: Female Fisher rats underwent ligation and division of the common bile duct or sham laparotomy. RESULTS: After obstruction, serum bilirubin and gamma-glutamyl transpeptidase rose to 24% and 30%, respectively, of maximum levels by 10 days after ligation. Morphologic evidence of proliferation of bile duct epithelial cells was first evident after 3 days. After hybridization to c-DNA probes, densitometry for H-ras and beta-actin revealed an immediate and parallel increase in steady-state levels of expression after 24 hours of cholestasis. Levels of c-myc messenger RNA were elevated during the first 3 days of cholestasis; however, at 7 and 10 days c-myc expression was depressed 16% and 60%, respectively. CONCLUSIONS: These profiles of expression show an oncogene response induced by early cholestasis. These data showed that elevations in H-ras and c-myc steady-state expression accompany the proliferative response of bile duct epithelial cells. Decreased levels of c-myc after initial elevation infer that ductal proliferation may continue independently of its steady-state expression, a response usually seen in vitro rather than in in vivo proliferation.

Congenital hemangiopericytoma: an unusual vascular neoplasm of infancy.

BACKGROUND: Hemangiopericytoma is an uncommon tumor of infants, which originates from the vascular pericytes. Although generally considered to benign, metastases can occur. METHODS: Five cases of congenital hemangiopericytoma were seen in infants; all were found in females. The mean age at diagnosis was 7 weeks (range, birth to 10 weeks). The lesions were located in the neck, the parotid, the axilla, and the retroperitoneum. One neck lesion was detected prenatally by ultrasonography. Each lesion was resected. The diagnosis of congenital hemangiopericytoma was established only after histologic examination. RESULTS: No evidence of recurrence has been found in four of the children. However, intrathoracic and intracranial metastases developed in one child with a neck lesion 28 months after the original resection, and the child was treated with chemotherapy, but she died of progressive disease. CONCLUSIONS: We advocate the consideration of congenital hemangiopericytoma in the newborn infant with a vascular mass. Because congenital hemangiopericytoma is unresponsive to steroid therapy, unlike other vascular malformations, resection is the treatment of choice. Long-term postoperative follow-up is essential for the early detection of metastases.

Focal infection of aortofemoral prostheses.

A canine model of unilateral aortofemoral bypass was utilized to study periprosthetic infections in woven, knitted, and velour Dacron vascular prostheses. These studies suggest that physical configuration, porosity, and time of inoculation all are important variables when managing an infected prosthesis, although size of inoculum seems less important.

Cholestasis without cirrhosis alters regulatory liver gene expression and inhibits hepatic regeneration.

Partial hepatectomy (PH) initiates cellular signals for regeneration. Sequential expression of nuclear and cytosolic protooncogenes accompanies the restoration of normal liver function and architecture. Although cirrhosis is known to inhibit liver regeneration, the effects of noncirrhotic cholestasis on hepatocellular proliferation, differentiation, and regulatory gene expression are unknown. To examine this, 25 male Fisher rats underwent common bile duct ligation and division. A 47% +/- 5% PH was performed 10 days after common bile duct ligation and division when histologic analysis revealed cholestasis without cirrhosis. Despite early elevations of total hepatic DNA and RNA values, cholestatic livers demonstrated a significant threefold suppression of expected hepatocyte mitotic indexes 48 and 72 hours after PH, compared with livers after PH alone. Weight restoration in cholestatic livers was 11% +/- 5.2% compared with 40% +/- 4.3% in control livers (+/- SEM; p less than 0.001) 5 days after PH. Analysis of regenerating liver messenger RNA with complementary DNA probes revealed an abnormal, sustained elevation of K-ras expression in cholestatic livers through all time points. Cholestasis blunted but did not obliterate normal sequential elevations in H-ras found in control livers. The expression of c-myc was inhibited threefold with cholestasis 72 hours after PH. These results are the first indication that cholestasis alone inhibits hepatocyte proliferation and the expression of c-myc that normally precedes the first wave of mitosis. This implies that cholestasis without cirrhosis may alter programmed liver gene expression, inhibiting normal hepatic regeneration.

Complement activation during prolonged extracorporeal membrane oxygenation.

Short-term cardiopulmonary bypass activates the complement system, possibly resulting in pulmonary dysfunction from granulocyte aggregation and pulmonary endothelial damage. These effects may be inhibited by steroids. Prolonged extracorporeal membrane oxygenation (ECMO) is used for newborn respiratory failure, but the effects of ECMO on complement activation are unknown. Twenty-one newborn infants with respiratory failure treated with ECMO were randomly assigned to group I (control, no steroids) or group II (30 mg/kg intravenous methylprednisolone before ECMO). Depletion assays of C3 and C5 were performed in each group at intervals before and during ECMO (declining values indicate complement activation). The groups were compared for complement levels, survival, time on ECMO and on the ventilator, and total hospitalization time. Steroids significantly shortened the time on ECMO and time on the ventilator after ECMO but did not affect survival or total hospitalization time. Steroids also enhanced activation of C3 and C5. Complement activation occurs during ECMO. Steroid administration paradoxically causes earlier complement activation but shortens ECMO and ventilator times. Complement activation during ECMO is of questionable significance. The benefits of steroids during ECMO may be mediated through other mechanisms.

A critical analysis of extracorporeal membrane oxygenation for congenital diaphragmatic hernia.

Despite advances made in the care of infants with congenital diaphragmatic hernia (CDH), survival remains poor. New therapy, such as extracorporeal membrane oxygenation (ECMO), is controversial but may improve survival. Thirty-two newborns with CDH were treated. Thirteen infants were treated with jugular vein-carotid artery ECMO after CDH repair elsewhere; six (46%) survived. Three of the remaining 19 were moribund shortly after birth and first received ECMO, then underwent repair; two (67%) survived. The other 16 underwent CDH repair; 8 of 9 (89%) recovered with conventional therapy, and 4 of 7 (57%) survived when ECMO was used after conventional therapy failed. Overall survival was 63%. Parameters with which physicians may attempt to predict survival or the need for ECMO after repair--such as A-aDO2, ventilatory index versus PCO2, presence of a "honeymoon period" (PaO2 greater than 100 mm Hg after repair), or oxygenation index--were unreliable. ECMO can improve survival in infants with CDH, probably through reversal of pulmonary hypertension. Presently available methods of predicting survival after CDH repair with or without ECMO are not accurate, and thus no infant should be excluded from repair or ECMO support.

Femoropopliteal bypass for limb salvage.

A total of 148 femoropopliteal bypass procedures followed for a minimum of 2 years yielded a patency rate of 61.9 percent among survivors. Diabetes mellitus, cigarette smoking, quality of the outflow, or prior inflow procedures did not influence patency rate. Results were less satisfactory in women and when cloth grafts were used. The indications for femoropopliteal bypass require continuing careful assessment.

Perforated appendicitis in children: risk factors for the development of complications.

BACKGROUND: Many aspects of the management of perforated appendicitis in children remain controversial. The objective of this study was to define risk factors associated with the development of postoperative complications in children undergoing treatment for perforated appendicitis. METHODS: We reviewed all children (age < 16 years) who were treated for perforated appendicitis at Cardinal Glennon Children's Hospital between 1988 and 1997. Inclusion criteria included either gross or microscopic evidence of appendiceal perforation. RESULTS: Of 285 children with perforated appendicitis, 279 underwent immediate operative treatment. Mean patient age was 7.7 years and there were no deaths. Major postoperative complications included intra-abdominal abscess (n = 17), ileus (n = 7), mechanical intestinal obstruction (n = 6), and wound infection (n = 4). All children who had a postoperative abscess had more than 5 days of symptoms before operation. Within this subgroup, drain placement was associated with not only decreased postoperative abscess formation and but also shorter duration of fever and length of hospitalization. The incidence of mechanical obstruction or ileus was not increased and the rate of wound infection was actually lower after drainage. CONCLUSIONS: Drain placement appears to be helpful in children with late diagnosis but is of little benefit when the duration of symptoms is less than 5 days. Thus it is likely that drains are most useful in patients with well-established and localized abscess cavities.

Toupét fundoplication for gastroesophageal reflux in childhood.

HYPOTHESIS: Gastroesophageal reflux (GER) is a common condition in childhood that frequently requires operative treatment. The 360 degrees Nissen fundoplication (NF) has been the standard operation for GER, but is associated with substantial rates of recurrence, "gas bloat," gagging, and dysphagia. I believe that the Toupet fundoplication (TF), a 270 degrees posterior wrap originally described in conjunction with myotomy for achalasia, has fewer complications, and its longterm outcome in children compared with NF is favorable. DESIGN: Nonrandomized controlled trial. SETTING: Tertiary care children's hospital. PATIENTS: Two hundred fifty-six children (aged 3 months to 16 years) with GER disease unresponsive to nonoperative therapy who underwent either NF (n = 102) or TF (n = 154). INTERVENTION: Operative repair of GER disease by either NF or TF. MAIN OUTCOME MEASURES: Time to first feeding, time to discharge from the hospital, postoperative dysphagia complications, recurrence, and rehospitalization and reoperation rates for each fundoplication technique. RESULTS: The 2 fundoplication techniques had equivalent recurrence rates, but TF had significantly lower rates of postoperative dysphagia (P = .008) and rehospitalization/reoperation rates (P = .005) and significantly shorter times to discharge from the hospital (P = .01) and to the first feeding (P = .02). CONCLUSIONS: These data show that both NF and TF are effective procedures for GER in children, with acceptable recovery times and low recurrence rates. However, TF results in earlier feeding and discharge from the hospital and has a significantly lower incidence of dysphagia, gagging, and gas bloat, resulting in fewer rehospitalizations. In this population, TF seems to be superior to NF.