Prospective randomised trial of endobronchial ultrasound-guide sheath versus computed tomography-guided percutaneous core biopsies for peripheral lung lesions.

AIM: To determine diagnostic rate, complications and patient tolerability of endobronchial ultrasound-guide sheath (EBUS-GS) and computed tomography (CT)-guided percutaneous core biopsy for peripheral lung lesions. METHODS: Lesions >1 cm diameter on CT were randomised to either EBUS-GS or CT-guided biopsy. Excluded were patients with severe chronic obstructive airway disease, lesions touching visceral pleura or hilum, and patients with symptoms needing bronchoscopic evaluation. Patients completed preprocedure and postprocedure questionnaires on tolerability. RESULTS: Of 64 participants (mean lesion size 29 ± 16 mm), 57 completed the study. Diagnostic sensitivity was 67% for EBUS-GS and 78% for CT-guided biopsy (P = not significant). In those with negative results, in the EBUS group, nine had a CT-guided biopsy as a cross-over, seven of which were positive. In the CT group, four had cross-over EBUS-GS of which three were diagnostic. Sensitivity for malignancy was 17/23 for EBUS-GS (74%) and 23/26 (88%, P = not significant). For lesions <2 cm, CT-guided biopsy had a significantly better diagnostic yield (80% vs 50%, P = 0.05). In EBUS-GS cases, for lesions with an air bronchogram, sensitivity was 89%. Pneumothorax and intercostal catheter insertion occurred in three and two cases, respectively, for EBUS, and 10 and 3 cases for CT-guided biopsy (P = 0.02 for pneumothorax). Nine unexpected admissions occurred after CT-guided biopsy compared with three after EBUS-GS. Overall, tolerability was high for both groups; however three patients had moderate-to-severe pain after CT-guided biopsy. CONCLUSIONS: In lesions <2 cm, CT-guided biopsy had higher yields; however, EBUS-GS had better tolerability and fewer complications.

The low-energy ion range in DNA.

In fundamental studies of low-energy ion irradiation effects on DNA, calculation of the low-energy ion range, an important basic physical parameter, is often necessary. However, up to now a unified model and approach for range calculation is still lacking, and reported data are quite divergent and thus unreliable. Here we describe an approach for calculation of the ion range, using a simplified mean-pseudoatom model of the DNA target. Based on ion stopping theory, for the case of low-energy (< or = a few keV) ion implantation into DNA, the stopping falls in the low reduced energy regime, which gives a cube-root energy dependence of the stopping (E(1/3)). Calculation formulas of the ion range in DNA are obtained and presented to unify the relevant calculations. The upper limits of the ion energy as a function of the atomic number of the bombarding ion species are proposed for the low-energy case to hold. Comparison of the results of this approach with the results of some widely used computer simulation codes and with results reported by other groups indicates that the approach described here provides convincing and dependable results.

Experimental comparison of time-of-flight mass analysis with magnetic mass analysis.

A series of experiments was carried out in which both a magnetic analyzer (mass separator) and a time-of-flight (TOF) spectrometer were used for ion charge/mass spectral analysis of the ion beam formed by a dc Bernas ion source made for semiconductor implantation. The TOF analyzer was a detachable device that provides rapid analysis of charge-to-mass composition of moderate energy ion beams. The magnetic analyzer was a massive device using a 90 degrees -sector bending magnet with radius of the central orbit of 35 cm. Comparison of these two methods for measuring ion beam composition shows good agreement.

Atomic force microscope nanolithography of polymethylmethacrylate polymer.

We describe a nanolithography process for a polymethylmethacrylate (PMMA) surface using scanning contact atomic force microscopy. Parallel furrows were scribed with a pyramidal silicon tip using the same scan mechanism as used to image samples. The PMMA was first electron beam irradiated using a scanning electron microscope and developed. The topography formed is reproducible and predictable. Material from the region where the tip scribes is moved to nearby regions, and aligned, elongated PMMA fragments are seen to decorate the valleys between furrows.

Small plasma source for materials application.

We describe a small hollow-cathode plasma source suitable for small-scale materials synthesis and modification application. The supporting electrical system is minimal. The gaseous plasma source delivers a plasma ion current of up to about 1 mA. Here we outline the source construction and operation, and present some of its basic performance characteristics.

Cell growth on 3D microstructured surfaces.

Chinese Hamster Ovary (CHO) cell cultures were grown on surfaces lithographed with periodic 3D hexagonal microcavity array morphology. The range of microcavity size (inscribed circle diameter) was from 12 µm to 560 µm. CHO cells were grown also on flat surfaces. The characterization was performed with respect to cell growth density (number of nuclei per unit area) by fluorescence optical microscopy and evaluated by correlation function analysis. We found that optimum microcavity radius was 80 µm, concerning to the maximum cell growth density, being even greater than the growth density on a flat (unstructured) substrate of the same material. This finding can be important for optimization of biotechnological processes and devices.

Pharyngeal cross-sectional area in normal men and women.

Pharyngeal size and the dynamic behavior of the upper airway may be important factors in modulating respiratory airflow. Patients with obstructive sleep apnea are known to have reduced pharyngeal cross-sectional area. However, no systematic measurements of pharyngeal area in healthy asymptomatic subjects are available, in part due to the lack of simple, rapid, and noninvasive measurement techniques. We utilized the acoustic reflection technique to measure pharyngeal cross-sectional area in 24 healthy volunteers (14 males, 10 females). Pharyngeal area was measured during a continuous slow expiration from total lung capacity (TLC) to residual volume (RV). We compared pharyngeal cross-sectional areas in males and females at three lung volumes: TLC, 50% of vital capacity (VC), and RV. In males, pharyngeal areas (means +/- SD) were 6.4 +/- 1.3 cm2 at TLC, 5.4 +/- 0.9 cm2 at 50% VC, and 4.1 +/- 0.8 cm2 at RV. In females, pharyngeal areas were 4.8 +/- 0.6 cm2 at TLC, 4.2 +/- 0.5 cm2 at 50% VC, and 3.7 +/- 0.6 cm2 at RV. The difference in area between males and females was statistically significant at TLC and 50% VC but not at RV. However, when the pharyngeal cross-sectional area was normalized for body surface area, this difference was not significant. In males there was a negative correlation of pharyngeal area with age. We conclude that sex differences in pharyngeal area are related to body size, pharyngeal area shows a similar variation with lung volumes in males and females, and in males pharyngeal area reduces with age.

Changes in tracheal cross-sectional area during Mueller and Valsalva maneuvers in humans.

Pressure-area behavior of the excised trachea is well documented, but little is known of tracheal compliance in vivo. Extratracheal tissue pressures are not directly measurable, but transmural pressure for the intrathoracic trachea is inferred from intra-airway and pleural pressure differences. Extramural pressure of the cervical trachea is assumed to be atmospheric. The difference in transmural pressure between the intra- and extrathoracic tracheal segments should be exaggerated during Mueller and Valsalva maneuvers. We used the acoustic reflection technique to measure tracheal areas above and below the thoracic inlet during these isovolume-pressure maneuvers. We found that 10 cmH2O positive pressure increased tracheal area in the extrathoracic segment by 34 +/- 16% (mean +/- SD) and in the intrathoracic segment by 35 +/- 15%. There was a reduction in area of 27 +/- 16 and 24 +/- 14%, respectively, for the extra- and intrathoracic segments with 10 cmH2O negative pressure. We conclude that the effective transmural pressure gradients do not vary significantly between intra- and extrathoracic tracheal segments.

Lung volume dependence of esophageal pressure in the neck.

There is conflicting evidence in the literature regarding tissue pressure in the neck. We studied esophageal pressure along cervical and intrathoracic esophageal segments in six healthy men to determine extramural pressure for the cervical and intrathoracic airways. A balloon catheter system with a 1.5-cm-long balloon was used to measure intraesophageal pressures. It was positioned at 2-cm intervals, starting 10 cm above the cardiac sphincter and ending at the cricopharyngeal sphincter. We found that esophageal pressures became more negative as the balloon catheter moved from intrathoracic to cervical segments, until the level of the cricopharyngeal sphincter was reached. At total lung capacity, esophageal pressures were -10.5 +/- 2.9 (SE) cmH2O in the lower esophagus, -18.9 +/- 3.0 just within the thorax, and -21.3 +/- 2.73 within 2 cm of the cricopharyngeal sphincter. The variation in mouth minus esophageal pressure with lung volume was similar in cervical and thoracic segments. We conclude that the subatmospheric tissue pressure applied to the posterior membrane of the cervical trachea results in part from transmission of apical pleural pressure into the neck. Transmural pressure for cervical and thoracic tracheal segments is therefore similar.

Gold ion implantation into alumina using an "inverted ion source" configuration.

We describe an approach to ion implantation in which the plasma and its electronics are held at ground potential and the ion beam is injected into a space held at high negative potential, allowing considerable savings both economically and technologically. We used an "inverted ion implanter" of this kind to carry out implantation of gold into alumina, with Au ion energy 40 keV and dose (3-9) × 10(16) cm(-2). Resistivity was measured in situ as a function of dose and compared with predictions of a model based on percolation theory, in which electron transport in the composite is explained by conduction through a random resistor network formed by Au nanoparticles. Excellent agreement is found between the experimental results and the theory.

Performance of an inverted ion source.

Whereas energetic ion beams are conventionally produced by extracting ions (say, positive ions) from a plasma that is held at high (positive) potential, with ion energy determined by the potential drop through which the ions fall in the beam formation electrode system, in the device described here the plasma and its electronics are held at ground potential and the ion beam is formed and injected energetically into a space maintained at high (negative) potential. We refer to this configuration as an "inverted ion source." This approach allows considerable savings both technologically and economically, rendering feasible some ion beam applications, in particular small-scale ion implantation, that might otherwise not be possible for many researchers and laboratories. We have developed a device of this kind utilizing a metal vapor vacuum arc plasma source, and explored its operation and beam characteristics over a range of parameter variation. The downstream beam current has been measured as a function of extraction voltage (5-35 kV), arc current (50-230 A), metal ion species (Ti, Nb, Au), and extractor grid spacing and beamlet aperture size (3, 4, and 5 mm). The downstream ion beam current as measured by a magnetically-suppressed Faraday cup was up to as high as 600 mA, and with parametric variation quite similar to that found for the more conventional metal vapor vacuum arc ion source.

Upgraded vacuum arc ion source for metal ion implantation.

Vacuum arc ion sources have been made and used by a large number of research groups around the world over the past twenty years. The first generation of vacuum arc ion sources (dubbed "Mevva," for metal vapor vacuum arc) was developed at Lawrence Berkeley National Laboratory in the 1980s. This paper considers the design, performance parameters, and some applications of a new modified version of this kind of source which we have called Mevva-V.Ru. The source produces broad beams of metal ions at an extraction voltage of up to 60 kV and a time-averaged ion beam current in the milliampere range. Here, we describe the Mevva-V.Ru vacuum arc ion source that we have developed at Tomsk and summarize its beam characteristics along with some of the applications to which we have put it. We also describe the source performance using compound cathodes.

High-energy metal ion implantation for reduction of surface resistivity of alumina ceramic.

In this work, the possibility to increase the surface conductivity of ceramic insulators through their treatment with accelerated metal ion beams produced by a MevvaV.Ru vacuum arc source is demonstrated. The increase in surface conductivity is made possible due to experimental conditions in which an insulated collector is charged by beam ions to a potential many times lower than the accelerating voltage, and hence, than the average beam ion energy. The observed effect of charge neutralization of the accelerated ion beam is presumably associated with electrons knocked out of the electrodes of the accelerating system of the source and of the walls of the vacuum chamber by the accelerated ions.

Environmental effects in Kelvin force microscopy of modified diamond surfaces.

We have explored the effects of atmospheric environment on Kelvin force microscopy (KFM) measurements of potential difference between different regions of test polycrystalline diamond surfaces. The diamond films were deposited by microwave plasma-assisted chemical vapor deposition, which naturally produces hydrogen terminations on the surface of the films formed. Selected regions were patterned by electron-beam lithography and chemical terminations of oxygen or fluorine were created by exposure to an oxygen or fluorine plasma source. For KFM imaging, the samples were mounted in a hood with a constant flow of helium gas. Successive images were taken over a 5-h period showing the effect of the environment on KFM imaging. We conclude that the helium flow removes water molecules adsorbed on the surface of the samples, resulting in differences in surface potential between adjacent regions. The degree of water removal is different for surfaces with different terminations. The results highlight the importance of taking into account the atmospheric environment when carrying out KFM analysis.

A high voltage pulse power supply for metal plasma immersion ion implantation and deposition.

We describe the design and implementation of a high voltage pulse power supply (pulser) that supports the operation of a repetitively pulsed filtered vacuum arc plasma deposition facility in plasma immersion ion implantation and deposition (Mepiiid) mode. Negative pulses (micropulses) of up to 20 kV in magnitude and 20 A peak current are provided in gated pulse packets (macropulses) over a broad range of possible pulse width and duty cycle. Application of the system consisting of filtered vacuum arc and high voltage pulser is demonstrated by forming diamond-like carbon (DLC) thin films with and without substrate bias provided by the pulser. Significantly enhanced film∕substrate adhesion is observed when the pulser is used to induce interface mixing between the DLC film and the underlying Si substrate.

Apneusis responding to buspirone in multiple sclerosis.

Apneusis is a disturbance of respiratory rhythm characterized by severely prolonged inspiratory effort, and is caused by bilateral lesions in the dorsal pons. In humans it is most commonly caused by pontine infarction and has rarely been reported in multiple sclerosis (MS). Here we report on a patient with MS who developed episodic apneusis which responded to treatment with buspirone, a serotonin type 1A receptor agonist.

Pharyngeal and glottic changes following methacholine challenge in normal subjects.

Recent evidence indicates that some normal subjects exhibit glottic narrowing following experimentally induced bronchospasm. Similar findings have been observed during episodes of bronchospasm in asthmatics. The exact mechanism of this effect is unknown but it is thought to occur as part of a generalized reflex response associated with constriction of intrapulmonary airways. We tested the hypothesis that in addition to the glottic changes, coincident with intrapulmonary airway constriction which occurred after inhalation of methacholine, the pharynx would show similar changes. Pharyngeal and glottic cross-sectional areas were measured using the acoustic reflection technique in seven healthy subjects before and after inhalation of metacholine. Before methacholine, pharyngeal and glottic areas (mean +/- SE) were 5.0 +/- 0.2 cm2 and 2.4 +/- 0.3 cm2 respectively. After inhalation of methacholine, these areas were reduced to 4.6 +/- 0.3 cm2 and 1.9 +/- 0.3 cm2 respectively (p less than 0.05). We conclude that inhalation of methacholine induces similar reductions in glottic and pharyngeal areas. The role of local or reflex mechanisms accounting for this reduction remains unclear.

Pleurectomy for persistent pain in benign asbestos-related pleural disease.

BACKGROUND: Persistent severe pain is a rare complication of benign asbestos-related pleural disease. METHODS: Four patients are described in whom pain persisted for more than one year (range 18 months to five years) which was incompletely relieved by opioid medication and nerve blocking procedures. All underwent pleurectomy in an attempt to relieve it. RESULTS: At operation the pleura was considerably thickened in all cases. Two of the four patients had successful relief of pain. The other two had a neuralgic component to their pain before surgery which persisted afterwards. One of these patients underwent successful cervical cordotomy. CONCLUSIONS: Pleurectomy may provide relief in patients with constant pleuritic pain due to benign asbestos-related pleural thickening. It seems, however, that patients in whom the pain has a neuralgic component are unlikely to benefit.

Pharyngeal compliance in snoring subjects with and without obstructive sleep apnea.

Recent studies have demonstrated a reduction in pharyngeal cross-sectional area and in upper airway muscle tone in patients with obstructive sleep apnea. These findings suggest that the pharynx in such patients may be more compliant than normal even in the awake state. We have tested this hypothesis by examining the pressure-area relationship of the pharynx in 13 patients and in 7 control subjects. Measurements were performed during wakefulness, with the subject seated, and at a constant lung volume near functional residual capacity. Pharyngeal area was measured by an acoustic reflection technique. Pharyngeal pressure was varied by having the subject perform gradual inspiratory and expiratory isovolume maneuvers against a distally occluded airway while mouth pressure was recorded. Specific compliance of the pharynx was calculated as the fractional change in pharyngeal area between a pressure of 0 and -10 cm H2O and and between 0 and 10 cm H2O. Specific pharyngeal compliance was 0.036 +/- 0.004 cm H2O-1 (mean +/- SE) in the control group and 0.094 +/- 0.012 cm H2O-1 in patients with OSA (p less than 0.01). These findings indicate that patients with obstructive sleep apnea have increased pharyngeal compliance. This abnormality predisposes to pharyngeal occlusion during sleep when negative transmural pressures are generated in the pharynx.