Upward movement of plutonium to surface sediments during an 11-year field study.

An 11-year lysimeter study was established to monitor the movement of Pu through vadose zone sediments. Sediment Pu concentrations as a function of depth indicated that some Pu moved upward from the buried source material. Subsequent numerical modeling suggested that the upward movement was largely the result of invading grasses taking up the Pu and translocating it upward. The objective of this study was to determine if the Pu of surface sediments originated from atmosphere fallout or from the buried lysimeter source material (weapons-grade Pu), providing additional evidence that plants were involved in the upward migration of Pu. The (240)Pu/(239)Pu and (242)Pu/(239)Pu atomic fraction ratios of the lysimeter surface sediments, as determined by Thermal Ionization Mass Spectroscopy (TIMS), were 0.063 and 0.00045, respectively; consistent with the signatures of the weapons-grade Pu. Our numerical simulations indicate that because plants create a large water flux, small concentrations over multiple years may result in a measurable accumulation of Pu on the ground surface. These results may have implications on the conceptual model for calculating risk associated with long-term stewardship and monitored natural attenuation management of Pu contaminated subsurface and surface sediments.

Virtue ethics in a pluralistic world.

The practice of pediatric surgery is at the crossroads of 2 specialties, pediatrics and surgery. At that vantage point, many ethical dilemmas can be seen. It is important for the pediatric surgeon to understand the special place of ethics in the care of children and how that care is influenced by society. The purpose of this report is to introduce the perspective of virtue ethics as an avenue to problem solving in ethical dilemmas in pediatric surgery. Virtue ethics relies more on the physician-focused view of character and ideal behavior as opposed to more patient-based rules of action. This ethical theory must be placed on the background of our changing society with an increasing plurality of values. The medical community of pediatric surgery must remain involved in the dialogue concerning these dilemmas in the care of children.

Telemedicine and pediatric surgery.

The practice of pediatric surgery has become increasingly demanding, requiring longer working hours with less reimbursement. Although manpower in this field is adequate, there are still areas that are underserved. Advances in technology offer the pediatric surgeon tools to improve efficiency of practice, cover wider areas of practice, and service underserved locations. The purpose of this report is to introduce the pediatric surgeon to telemedicine technology and its potential impact on the practice environment. The history, key components, and current applications of telemedicine are presented. The ability to integrate this technology in pediatric surgical practice holds great potential.

Development and laboratory evaluation of a new toothbrush with a novel brush head design.

Despite many developments in manual toothbrush design, plaque removal at the back of the mouth and at approximal surfaces remains inadequate, yet it is at these sites in particular that plaque accumulates and leads to the development of gingival disease. Improved oral hygiene can be achieved by better brushing technique and by increasing brushing time, but a change in behavior patterns is almost impossible to achieve for the majority of individuals. What is required is a brush head design that maximizes plaque removal, regardless of how the user brushes. As a result of a detailed investigation into the action of bistles during brushing, the Oral-B CrossAction toothbrush has been developed. It incorporates bristles angled at 16 degrees in a unique CrissCross design arranged along the horizontal axis of the toothbrush. Laboratory studies have demonstrated that this development significantly enhances interproximal penetration and cleaning effectiveness when compared with an identical brush head with vertical rather than angled bristles. Laboratory comparisons with more than 80 leading manual toothbrushes from around the world demonstrate a consistent, significant advantage for the new CrossAction toothbrush, both with respect to interproximal penetration and cleaning effectiveness. These results suggest that the CrossAction toothbrush has the potential to remove greater amounts of plaque, especially from the approximal surfaces, than conventional toothbrushes incorporating vertical bristles or more traditional tuft designs.

Tritium and plutonium in waters from the Bering and Chukchi seas.

During the summer of 1993, seawater in the Bering and Chukchi Seas was sampled on a joint Russian-American cruise [BERPAC] of the RV Okean to determine concentrations of tritium, 239Pu and 240Pu. Concentrations of tritium were determined by electrolytic enrichment and liquid scintillation counting. Tritium levels ranged up to 420 mBq L(-1) and showed no evidence of inputs other than those attributed to atmospheric nuclear weapons testing. Plutonium was recovered from water samples by ferric hydroxide precipitation, and concentrations were determined by thermal ionization mass spectrometry. 239+240Pu concentrations ranged from < 1 to 5.5 microBq L(-1). These concentrations are lower than those measured in water samples from other parts of the ocean during the mid-1960's to the late 1980's. The 240Pu:239Pu ratios, although associated with large uncertainties, suggest that most of the plutonium is derived from world-wide fallout. As points of comparison, the highest concentrations of tritium and plutonium observed here were about five orders of magnitude lower than the maximum permissible concentrations allowed in water released to the off-site environs from licensed nuclear facilities in the United States. This study and others sponsored by the International Atomic Energy Agency and the Office of Naval Research's Arctic Nuclear Waste Assessment Program are providing data for the assessment of potential radiological impacts in the Arctic regions associated with nuclear waste disposal by the former Soviet Union.

Vaginal agenesis discovered during repair of high imperforate anus: operative management.

A girl born with laryngeal stenosis, tracheal esophageal fistula and esophageal atresia, imperforate anus, duodenal atresia, and Mayer-Rokitansky-Kuster-Hauser syndrome is presented. An explanation of the abnormalities and the surgical approach are presented.

Reverse-torque failure of screw-shaped implants in baboons after 6 months of healing.

Mechanical testing of the implant-tissue interface has been the focus of numerous investigations concerning the anchorage capacity of implants. The purpose of this study was to measure reverse-torque failure after 6 months of healing for three different biomaterials in the posterior jaws of four adult female baboons. The animals had all of their posterior teeth surgically extracted and, following 10 weeks of healing, 7 implants were placed in each quadrant. The biomaterials included titanium plasma-sprayed surfaces, titanium-aluminum-vanadium surfaces (both 3.8 mm x 10 mm), and a commercially pure titanium surface (3.75 mm x 10 mm). After 6 months, torque data were collected using a counterclockwise computerized torque driver and were analyzed by repeated measures analysis of variance for differences related to biomaterial, jaw, and biomaterial/jaw. Post-hoc Tukey Kramer analysis was also performed for within-group differences (alpha = .05 level). The biomaterial comparison revealed a significant difference between the titanium plasma-sprayed and the combined commercially pure titanium/titanium -aluminum-vanadium groups (analysis of variance, Tukey Kramer, P < .05). The jaw comparison showed no significant difference, although the data suggest that higher forces may be required for mandibular torsional failure. The biomaterial/jaw comparison revealed that jaw differences for the mean values of commercially pure titanium and titanium-aluminum-vanadium implants were greater than jaw differences for mean values of titanium plasma-sprayed implants, although these differences were not statistically significant. Because of the lack of correlation between single-cycle biomechanical tests and clinical performance, it is necessary to be selective in assigning usefulness to data of this type.

Sources of support for learning words in conversation: evidence from mealtimes.

This study examines mealtimes of preschoolers' families to determine whether rare words are used in informative ways so that a child could learn their meanings. Is there an association between informative use of rare words and the child's later vocabulary? Each use of rare words in 160 transcripts was coded for whether it was informative or uninformative. Each informative exchange was coded for type of strategy used to provide support: physical or social context, prior knowledge, and semantic support. There were 1,631 exchanges around rare words. About two-thirds of these exchanges were informative uses from which the child could learn the word's meaning. The most frequent strategy used was semantic support, accounting for two-thirds of strategies used. The frequency of use of rare words was positively correlated with age-five and age-seven PPVT scores.

Technetium-99, iodine-129 and tritium in the waters of the Savannah River Site.

Surface water samples were collected from streams on and around the Savannah River Site (SRS) to assess current 3H, 99Tc, and 129I concentrations in the water. The SRS is a nuclear facility operated by Westinghouse Savannah River Company for the US Department of Energy. Water quality parameters were measured at the time of collection using field portable instrumentation. The tritium activity was determined by liquid scintillation spectrometry. The isotopes, 99Tc and 129I, were determined by isotope dilution/inductively coupled plasma-mass spectrometry (D.M. Beals, Determination of technetium-99 in aqueous samples by isotope dilution inductively coupled plasma-mass spectrometry. Presented at the 3rd International Conference on Nuclear and Radiochemistry, Vienna, September 1992, unpublished data; D.M. Beals, P. Chastagner and P.K. Turner, Analysis of iodine-129 in aqueous samples by inductively coupled plasma-mass spectrometry. Presented at the 38th Annual Conference on Bioassay, Analytical and Environmental Radiochemistry, Santa Fe, NM, November 1992). Elevated activities of 3H, 99Tc, and 129I were found in some surface streams of the SRS, principally due to migration of ground water from beneath old seepage basins, however the levels in the waters leaving the SRS are well below any regulatory guidelines.

Comparison of the resistance of miniplates and microplates to various in vitro forces.

A comparison of the Luhr Mini System (Howmedica, Inc, Rutherford, NJ) and the Luhr Micro System (Howmedica, Inc) was undertaken to determine resistance to various forces using a biomechanical model. Miniplates and microplates were first tested to determine their resistance to forces of displacement on flat bend, edge bend, tension, and compression generated by a materials testing system machine. Then, miniplates and microplates were attached to fresh porcine ribs, fixed to a custom-made jig, and subjected to the same forces of displacement. The load was applied to the bone plate to permanent deformation in all tests. The mini and microplate systems resisted 14.50 and 1.14 kg, respectively, on edgewise bending, 2.65 and 1.10 kg, respectively, on flat bending, 92.03 and 16.44 kg, respectively, on tension, and 127.9 and 27.02 kg, respectively, on compression. The mini and microsystem biomechanical model resisted 1.89 and 0.94 kg, respectively, on edgewise bending, 5.20 and 0.85 kg, respectively, on flat bending, 37.60 and 15.72 kg, respectively, on tension, and 53.55 and 16.0 kg, respectively, on compression. The results suggest that the Luhr Mini Fixation System provides a significant amount of resistance to tensile and compressive forces, but is weakest when large forces are applied at 90 degrees to the flat portion of the plate. The system showed decreased force resistance in the biomechanical model except on flat bending. The Luhr Micro Fixation System has significantly less resistance to deformation, but shows no decrease in ability to resist forces of displacement in the biomechanical model.

Environmental monitoring and dose assessment following the December 1991 K-reactor aqueous tritium release.

Between 22 December and 25 December 1991, approximately 570 L of tritiated water was released from the K Reactor at the Savannah River Site. Analyses of river flow rates and measured tritium concentrations showed that approximately 210 TBq of tritium had been released from the reactor and was being transported down the Savannah River. Elevated tritium concentrations in the Savannah River were first detected on 26 December 1991. The maximum measured tritium concentration at Highway 301 (a major sampling point 37 km downstream of the Savannah River Site) was 2.5 Bq mL-1. A hypothetical maximum individual located at Highway 301 would have received a drinking water dose of approximately 0.35 microSv, less than 1% of the Environmental Protection Agency's 40 microSv y-1 drinking water standard. Concentrations at the intake canals to two water treatment facilities, approximately 160 km downstream, began to rise above normal on 28 December. The population dose to users of the downstream domestic water supplies and consumers of Savannah River biota was estimated to be 4.7 x 10(-3) person-Sv.

Aminocaproic acid decreases the incidence of intracranial hemorrhage and other hemorrhagic complications of ECMO.

Since the inception of extracorporeal membrane oxygenation (ECMO), hemorrhage has been a major complication often limiting its usefulness. This study was undertaken to evaluate the effect of aminocaproic acid (AMICAR), an inhibitor of fibrinolysis, on all hemorrhagic complications of ECMO including intracranial hemorrhage (ICH). In 1990, 49 neonates and 5 older children received ECMO therapy. None of these patients received AMICAR. In 1991, 51 neonates and 5 older children received ECMO. Forty-two of these patients who were considered to be at high risk for bleeding complications (preexisting or anticipated surgical procedures, preexisting ICH, or profound hypoxia, acidosis, coagulopathy, or prematurity) were given AMICAR. The remaining 14 low-risk neonates did not receive AMICAR, and for purposes of analysis were combined with the 1990 group. AMICAR was administered just prior to or after cannulation (100 mg/kg, intravenously) and was infused continuously at 30 mg/kg/h until decannulation. Except for the addition of AMICAR, the ECMO protocol was identical for these two patient groups. Patients who received AMICAR had significantly less bleeding while on ECMO (P = .03) and required fewer blood transfusions (P = .01) than patients not receiving AMICAR. This difference was most significant in the congenital diaphragmatic hernia and cardiac subgroups (P = .0001) and was not significant in the meconium aspiration subgroup (P = .1). The incidence of ICH in the neonatal subgroup was also significantly reduced with no patient on AMICAR developing a new or extending a preexisting ICH (P = .007). Reexploration of the cannulation site for bleeding was also reduced in the AMICAR-treated group but the difference failed to reach statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary growth and remodeling in infants with high-risk congenital diaphragmatic hernia.

Infants born with congenital diaphragmatic hernia (CDH) have pulmonary hypoplasia, but the pattern of postnatal growth in these lungs has not been documented. The lungs of 21 children dying with CDH were analyzed to determine how the pulmonary morphology changed with age. The patients were stratified into three age groups for ANOVA analysis (less than 8 days, 8 to 21 days, greater than 21 days). Morphometric techniques previously described were used. Lung volume and weight as well as pulmonary artery length and diameter increased with age (P = .04), whereas the number of airway generations was similar for each group. Radial alveolar number also increased, particularly in the contralateral lung (P = .02). The percentage of intraacinar artery muscularization decreased with age (P = .02), while larger intraacinar arteries showed a nonmuscular structure, again particularly in the contralateral lung (P = .004). It is concluded that: (1) significant lung growth does occur postnatally at the alveolar level after CDH repair; and (2) there is postnatal vascular remodelling resulting in larger and less muscular arteries. These changes should contribute to a decrease in pulmonary arterial hypertension over time. However, the time period over which these changes occur exceeds the current limitations of invasive support measures such as extracorporeal membrane oxygenation. Elucidation of the factors responsible for this growth could result in new therapeutic strategies to enhance or accelerate postnatal pulmonary development in infants with CDH.

Blastomycosis of the lung: CT features.

The authors reviewed the computed tomographic (CT) scans in 16 patients with pulmonary blastomycosis to describe the abnormalities seen at CT. The CT features were as follows: mass lesions (n = 14), consolidation (n = 9), air bronchograms (n = 14), intermediate-sized nodules (n = 12), satellite lesions (n = 11), pleural thickening (n = 4), small effusions (n = 2), and cavitation (n = 2). One patient had noncalcified hilar lymphadenopathy. Eight patients had acute disease, six had chronic disease, and two had acute exacerbation of a chronic illness. Fifteen patients had cough, fever, and/or dyspnea. Two patients underwent surgical resection for the presumptive diagnosis of bronchogenic carcinoma. In general, there was no correlation between the radiologic abnormalities and the clinical presentation. Consolidation occurred more frequently in acute disease. CT may be useful to help define the radiologic findings and distribution of disease. Familiarity with the characteristic CT findings of pulmonary blastomycosis may encourage an expeditious diagnostic approach to identify the disease and, possibly, prevent unnecessary surgical resection.

Management of bacterial pneumonia in ventilated patients. Protected bronchoalveolar lavage as a diagnostic tool.

We conducted a prospective study to determine the effectiveness of protected bronchoalveolar lavage (PBAL) in diagnosing pneumonia in ventilated patients and the usefulness of bronchoscopic data in treating ventilated patients. Entrance criteria were (1) fever and a new or progressive infiltrate on chest roentgenogram with either leukocytosis or a macroscopically purulent tracheal aspirate, and (2) no antibiotic therapy for at least 48 h before bronchoscopy. Twenty-five ventilated patients met entrance criteria for the study and completed the protocol. PBAL was effective in retrieving distal airway secretions with a minimal degree of contamination as indicated by a specificity and a negative predictive value of 100 percent. Bacterial isolates grew in all patients with pneumonia at a concentration greater than or equal to 100,000 cfu/ml, with a median growth of 500,000 cfu/ml. The presence of a two-log difference between the highest quantitative culture count in patients without pneumonia and the lowest quantitative culture count in patients with pneumonia allowed a clearer determination of a patient's status, with regard to pneumonia, compared with the significant overlap in unprotected BAL. Gram and Giemsa stains of the PBAL were positive in all patients with pneumonia and negative in those without pneumonia. All but one patient with pneumonia received narrow-spectrum antibiotic therapy. All patients without infection had no antibiotic administered. Clinical and roentgenographic criteria could not discriminate between patients with and without pneumonia, confirming the findings of previous investigations. The results of microscopic and culture analyses of the PBAL effluent proved useful in directing antibiotic treatment in patients with pneumonia and in avoiding unnecessary antibiotic use in those patients without pneumonia.

Carcinoma of the male breast: a 27-year community experience.

Carcinoma of the male breast is relatively rare and the prognosis is usually more ominous than in the female. Radical mastectomy is advocated for optimal therapy but lesser procedures are used for a variety of reasons. After observing several recent cases of male breast cancer, we reviewed the tumor registries for the past 27 years at Marshall University affiliated hospitals. Thirteen cases were found and evaluated. This article presents treatment, survival and a review of the current therapy.