Learning curve for robotic esophagectomy and dissection of bilateral recurrent laryngeal nerve nodes for esophageal cancer.

Dissection of bilateral recurrent laryngeal nerve (RLN) nodes is a technically demanding procedure, but robotic systems have been useful for RLN node dissection. This retrospective study investigated the learning curve for bilateral RLN node dissection in esophageal-cancer patients using a robotic system for esophageal cancer. We retrospectively reviewed 33 consecutive patients who received a robotic esophagectomy and total lymphadenectomy by single surgeon. The patients were divided into either group 1 (initial 20 cases) or group 2 (later 13 cases). The mean patient age was 61.88 ± 9.03 years and 28 (84.8%) patients were male. Most cases were pathologically diagnosed as squamous cell carcinoma. The lesion locations included 3 (9.1%) in the upper esophagus, 12 (63.6%) in the mid esophagus, and 9 (27.3%) in the lower esophagus. Eleven (33.3%) cases were stage I, 7 (21.2%) were stage II, and 15 (45.5%) were stage III. One case in group 2 (3%) suffered operative mortality. Operation time, robot console time, and blood loss were similar between the two groups. The timing of right and left RLN node dissection, the number of total dissected lymph nodes, and the percentage of dissected right and left RLN nodes were also comparable. However, the incidence of vocal cord palsy was significantly lower in group 2 (55% vs. 0%, p= 0.02). The incidence of other operative complications did not vary between the two groups. Even though operative outcomes and incidence of other complications were comparable between the two groups, the incidence of vocal cord palsy decreased significantly after 20 cases. Thus, we conclude that a minimum of 20 cases is required before a surgeon is experienced enough to perform safe dissection of bilateral RLN nodes.

New predictive equation for lung volume using chest computed tomography for size matching in lung transplantation.

PURPOSE: Lung size matching is important in lung transplantation (LT). With advances in computed tomography (CT) technology, multidetector row CT can accurately measure the thoracic cage and lung volumes. The objective of this study was to generate a new regression equation using demographic data based on the measured CT lung volume in a healthy population to predict the CT lung volume of the donor in LT size matching. MATERIALS AND METHODS: The medical records of healthy subjects who underwent chest CT scans to screen for lung cancer were retrospectively reviewed. CT lung volume was semi-automatically measured using a threshold-based auto-segmentation technique. New regression equations for CT lung volume were generated by multiple linear regression analysis using demographic data including height (H, cm), weight (W, kg), and age (A, years). The percentage error rate (%) of the equations were calculated as ([Estimated CT lung volume--Measured CT lung volume]/Measured CT lung volume × 100). A percentage error rate within ± 20% was considered acceptable. RESULTS: A total of 141 men aged 27 to 55 years (mean, 46.7 ± 6.2 years) and 128 women aged 20 to 55 years (mean, 45.4 ± 7.2 years) were enrolled. The final regression equations for CT lung volume were (-5.890 + 0.067 H - 0.030 W + 0.020 A) in men and (-6.698 + 0.072 H - 0.024 W) in women. The mean absolute error rate was 10.9 ± 9.0% and 11.0 ± 8.5% in men and women, respectively. Percentage error rates were within ± 20% in 121 of 141 (85.8%) men and 113 of 128 (88.3%) women. CONCLUSION: These equations could predict the CT lung volume of healthy subjects using demographic data. Using these equations, the predicted CT lung volume of donors could be matched to the measured CT lung volume of recipients in lung transplantation.

HRCT features of acute rejection in patients with bilateral lung transplantation: the usefulness of lesion distribution.

PURPOSE: This study sought to evaluate the high-resolution computed tomography (HRCT) features of acute rejection and to assess the diagnostic accuracy of HRCT for acute rejection considering distribution of lesions in patients with bilateral lung transplantation (BLT). MATERIALS AND METHODS: Between March 2010 and June 2012, 48 transbronchial lung biopsies (TBLBs) and HRCT were performed simultaneously in 26 patients who underwent BLT. We evaluated the presence of ground glass opacity (GGO), consolidation, nodule, bronchial wall thickening, interlobular septal thickening, pleural effusion, atelectasis, bronchiectasis, and cardiomegaly on the HRCT images. The distribution of lesions was analyzed according to bilaterality or upper/lower predominance. Acute rejection was determined on the basis of the pathologic results of TBLB. We evaluated potential correlations of HRCT features with acute rejection, then assessed overall diagnostic accuracy of various HRCT features in combination to diagnose acute rejection in the transplanted lung. RESULTS: Among the 48 TBLBs, 8 were diagnosed as acute rejection (A1, 4 cases; A2, 2 cases; and A3, 2 cases) pathologically. Two A1 rejections and one A2 rejection appeared normal on computed tomography images. Without considering the distribution of lesions, interlobular septal thickening was significantly associated with acute rejection (P = .010) only. Regarding the distribution of lesions on HRCT images, not only interlobular septal thickening but also GGO was significantly associated with acute rejection (P < .05). The sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of the HRCT scan in the evaluation of acute rejection were 50%, 97.5%, 80%, 90.1%, and 89.6%, when the bilateral GGO and interlobular septal thickening with lower predominance were considered as the positive finding. CONCLUSIONS: HRCT findings considering lesion distribution could be a useful tool in diagnosing acute rejection in patients with BLT.

The fate of patients on the waiting list for lung transplantation in Korea.

Lung transplantation for end-stage lung disease results in prolonged actuarial survival and improved pulmonary function. However, the shortage of donor lungs has been a major limiting factor in transplantation. The purpose of this study was to analyze the waiting time and mortality rate for each disease entity. The medical records of all patients listed in The Korean Network for Organ Sharing (KONOS) from May 1996 to May 2011 were analyzed to identify waiting times and causes of death. During the study period, 146 patients (86 males and 60 females) of mean age of 46.6 years (range; 5 to 73 years) showed idiopathic pulmonary fibrosis (IPF; n = 61), chronic obstructive pulmonary disease (COPD; n = 19) or bronchiectasis (n = 15). Sixty-five patients (44.5%) underwent lung or heart-lung transplantation. Sixty-two patients (42.5%) expired during the waiting period, and 19 patients are still on the waiting list. The mortality rate while waiting was highest among patients with primary pulmonary hypertension (62.5%) followed by IPF (57.4%), and acute respiratory distress syndrome (ARDS) (55.6%). The mean time from diagnosis to registration in KONOS was 15.5 months among the expired and 13.2 months in the transplanted group (P = .455). The mean time on waiting list was 8.2 months in the expired group and 3.7 months in the transplanted group (P = .012). In the expired group, the mean survival time was significantly shorter among patients with ARDS (2.2 months, P = .004) compared to IPF (7.9 months), COPD (10.7 months), and primary pulmonary hypertension (PPH) (30.0 months). The high mortality rate (42.5%) during the waiting period in Korea may result from the lack of donors and the delay in registration.

Donor evaluation for lung transplantation in Korea.

Lung transplantation for end-stage lung disease results in prolonged survival and improved pulmonary function. However, the shortage of donor lungs has been a major limiting factor in Korea. We sought to investigate the number and utilization of donor lungs by the five institutions performing LTx in Korea, retrospectively reviewing outcomes of organs registered in the Korean Network for Organ Sharing from January to December, 2010. Lungs were offered from 270 brain-dead patients (189 males and 81 females) of mean age of 45.2 ± 14.2 years (range, 12 to 77 years). The most common cause of brain death was hemorrhage (n = 219, 81%). Only 18 (6.7%) donor lungs were used, which was low compared with kidney (93.3%), liver (86.3%), heart (26.7%), and pancreas (11.1%) use. The mean age of donors of transplanted lungs was 35.7 years (range, 14 to 51 years) compared with 45.9 years for other organs (P = .003). The characteristics of utilized donor lungs were: mean partial pressure of oxygen (PaO(2)), 300.9 mm Hg; mean smoking history, as 2.7 pack-years; and mean body mass index, 21.2 kg/m(2). The causes of refusal were medical ineligibility (n = 129) including poor PaO(2), abnormal chest x-ray, long smoking history, older age (n = 46), no properly matched recipient (n = 46), unknown (n = 17), and family withdrawal (n = 14). Only 8 (33.3%) were transplanted from standard criteria and 10 from the lungs that did not satisfy these criteria. An efficient utilization system is needed to improve lung transplantations.

Oesophagography and oesophagoscopy are not necessary in patients with spontaneous pneumomediastinum.

BACKGROUND: Because the condition is rare, the proper assessment of spontaneous pneumomediastinum (SPM) remains controversial. The purpose of this study was to determine whether additional oesophageal investigations beyond chest x ray and chest computed tomography (CT) scan are necessary for the diagnosis of SPM. METHODS: The medical records of 25 patients diagnosed and treated for SPM from March 1986 to December 2007 were retrospectively reviewed. RESULTS: There were 22 men and 3 women, with a median age of 19 years (range 15-57 years). All patients received chest x rays, which revealed air shadows within the mediastinum or subcutaneous emphysema in 24 patients. Twenty-two patients underwent chest CT scans, which showed pneumomediastinum in all cases. Oesophagography was performed in 14 patients and oesophagoscopy in three. All oesophagographies and oesophagoscopies were clear. Despite conservative treatment, no patients developed mediastinitis or complications associated with oesophageal injury. CONCLUSIONS: Chest x ray and CT scan are sufficient to diagnose SPM. Additional diagnostic assessments such as oesophagography and oesophagoscopy are not necessary in patients without evidence of mediastinitis or a history of oesophageal injury.

Observation of a multiferroic critical end point.

The study of abrupt increases in magnetization with magnetic field known as metamagnetic transitions has opened a rich vein of new physics in itinerant electron systems, including the discovery of quantum critical end points with a marked propensity to develop new kinds of order. However, the electric analogue of the metamagnetic critical end point, a "metaelectric" critical end point, has been rarely studied. Multiferroic materials wherein magnetism and ferroelectricity are cross-coupled are ideal candidates for the exploration of this novel possibility using magnetic-field (H) as a tuning parameter. Herein, we report the discovery of a magnetic-field-induced metaelectric transition in multiferroic BiMn(2)O(5), in which the electric polarization (P) switches polarity along with a concomitant Mn spin-flop transition at a critical magnetic field H(c). The simultaneous metaelectric and spin-flop transitions become sharper upon cooling but remain a continuous cross-over even down to 0.5 K. Near the P = 0 line realized at mu(0)H(c) approximately 18 T below 20 K, the dielectric constant (epsilon) increases significantly over wide field and temperature (T) ranges. Furthermore, a characteristic power-law behavior is found in the P(H) and epsilon(H) curves at T = 0.66 K. These findings indicate that a magnetic-field-induced metaelectric critical end point is realized in BiMn(2)O(5) near zero temperature.

An overview of lung transplantation in Korea.

OBJECTIVE: Lung transplantation (LTx) is the only option for end-stage lung disease refractory to medical treatment. The program was slow to start in Korea; the first LTx was performed in July 1996. By October 2007, 25 lung and 7 heart-lung transplantations have been performed at 5 institutes, with the majority being performed at one center. The aim of this study was to improve the survival rate following LTx by analyzing the operative procedure and its complications. METHODS: We performed a retrospective review of the medical records of 18 patients who underwent lung and heart-lung transplantations from July 1996 to October 2007 at a single institute. Operative mortality was excluded from the analysis of early and late complications. RESULTS: There were 12 males and 6 females of mean age 46.2 +/- 11.5 years (range, 25-63 years). The indications for transplantation included pulmonary emphysema (n = 6), idiopathic pulmonary fibrosis (n = 3), lymphangioleiomyomatosis (n = 3), Eisenmenger's syndrome (n = 2), bronchiectasis (n = 2), primary pulmonary hypertension (n = 1), and primary graft dysfunction after a single lung transplantation (SLT; n = 1). Operations consisted of SLTs in 9 patients, bilateral sequential single lung transplantations (BSSLTs) in 8 patients, and a heart-lung transplantation (HLT) in 1 patient. Early complications were bleeding necessitating rethoracotomy, severe reperfusion injury, seizure, prolonged airleak, chylothorax, and pulmonary artery stenosis. Late complications consisted of cytomegalovirus infection, pulmonary tuberculosis, posttransplantation lymphoproliferative disease, gastric ulcer perforation, pneumothorax, chylothorax, empyema, and aspergillosis. There were 5 operative deaths due to intraoperative bleeding (n = 1), acute graft dysfunction (n = 2), and multiorgan failure (n = 2). Excluding the operative mortality, the mean survival period was 18.5 +/- 23.7 months (range, 3-87 months). CONCLUSIONS: Clinical experience in recent years may have reduced complication rates and led to prolonged survival. Increasing the candidate list through better results and raising awareness of the LTx program is necessary to move forward with thoracic transplantation in Korea.

Preparation of poly epsilon-caprolactone nanoparticles containing magnetite for magnetic drug carrier.

Magnetic poly epsilon-caprolactone (PCL) nanoparticles were prepared in a well shaped spherical form by the o/w emulsion method. The influence of some preparative variables on the size and surface property was investigated. Nanoparticles were smooth, well individualized and homogeneous in size. The presence of magnetite and its superparamagnetic characteristic were confirmed by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM), respectively. The anti-cancer drug was encapsulated in the magnetic nanoparticle during preparation. A typical release behavior was observed for 30 days. In vitro experiment of magnetic susceptibility under external magnetic field demonstrated that the magnetic PCL nanoparticles have sufficient magnetic susceptibility for a potential magnetic drug carrier for targeted delivery.

Magnetic PECA nanoparticles as drug carriers for targeted delivery: synthesis and release characteristics.

Magnetic poly(ethyl-2-cyanoacrylate) (PECA) nanoparticles containing anti-cancer drugs (Cisplatin and Gemcitabine) were prepared by inter-facial polymerization. The spherical nanoparticles (d = 250 +/- 15 nm) with smooth surfaces and moderately uniform size distributions were obtained. The amount of magnetite encapsulated inside the polymer matrix was increased up to 14.26% (w/w) by controlling the initial weight ratio of monomer/magnetite. It was found that the amount of Cisplatin encapsulated in the magnetic nanoparticle is much higher than that of Gemcitabine because Cisplatin (hydrophobic) is highly soluble in the oil phase and encapsulated easier inside nanoparticles compared to Gemcitabine (hydrophilic). The presence of magnetite and its super-paramagnetic characteristic were confirmed by FTIR spectra and VSM. In-vitro experiments of drug release and magnetic mobility under external magnetic field demonstrated that magnetic poly(ethyl-2-cyanoacrylate) (PECA) nanoparticles can be a highly versatile magnetic drug carrier with sustained release behaviour and sufficient magnetic susceptibility.

Ca-alginate microspheres encapsulated in chitosan beads.

Chitosan beads (CBs) incorporating Ca-alginate microspheres (CAMs), containing a drug, were prepared as an oral sustained delivery system. Stable and monodisperse Ca-alginate microspheres loaded with drug were obtained by a membrane emulsification method. The Ca-alginate microspheres were encapsulated in chitosan beads by the ionotropic gelation method with a polyelectrolyte complex reaction between two oppositely charged polyions. The surface and internal characteristics of the beads were improved by ionic cross-linking in tripolyphosphate (TPP) solution adjusted to pH 5.0. The release experiments were performed using lidocaine.HCl (cationic drug) and sodium salicylate (anionic drug) as model drugs. Initial release of drugs depended on the degree of swelling. Ca-alginate microspheres encapsulated in chitosan beads were superior to both drug-loaded CBs and CAMs beads for sustained release because they had a three-layer composition; a calcium alginate core bounded by an inter-phasic chitosan-alginate membrane, which itself was surrounded by a layer of chitosan-TPP.

Preparation of chitosan microspheres using membrane emulsification and its size modelling.

The chitosan microspheres were prepared by a membrane emulsification method with variations of the N2 gas pressure and the chitosan concentration. The pressure of N2 gas was varied within the range from 0.2 x 10(5) to 0.8 x 10(5) Pa at chitosan concentration 1.5 wt%. In addition, the concentration of chitosan was varied between 0.5 approximately 2.0 wt% at 0.4 x 10(5) Pa of N2 gas pressure. Using this method, it is possible to prepare stable emulsions with a very narrow droplet size distribution in comparison with conventional methods. The average size of the microspheres was dependent on the N2 gas pressure and the concentration, that is it was increased with the pressure and the concentration. The modelling of the size for the microspheres according to the concentration was carried out using Macleod's relation and Parkins & Brown equation. The former shows the relationship between density and surface tension and the latter demonstrates the correlation between the volume of the microspheres and the interfacial tension. The modelling results were in good agreement with the experimental data to predict the microspheres size with the variation of concentration.

Enhanced secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae by translational fusion to cellulose-binding domain.

The secretion of Bacillus stearothermophilus L1 lipase in Saccharomyces cerevisiae was investigated by employing a fusion partner, a cellulose-binding domain (CBD) from Trichoderma harzianum endoglucanase II (THEG). The CBD was connected to the N-terminal of L1 lipase through an endogenous linker peptide from THEG. The expression cassette for the fusion protein in S. cerevisiae was constructed using the alpha-amylase signal peptide and the galactose-inducible GAL10 promoter. Secretion of CBD-linker-L1 lipase by this fusion construct was dramatically 7-fold enhanced, compared with that of the mature L1 lipase without CBD-fusion. The fusion protein was secreted into the culture medium, reaching levels of approximately 1.3 g/l in high-cell-density fed-batch cultures. Insertion of a KEX2 cleavage site into the junction between CBD-linker and L1 lipase resulted in the same level of enhanced secretion, indicating that the CBD-linker fusion probably plays a critical role in secretion from endoplasmic reticulum to Golgi apparatus. Therefore, the CBD from THEG can be used both as an affinity tag and as a secretion enhancer for the secretory production of heterologous proteins in S. cerevisiae, since in vivo breakage at the linker was almost negligible.

Biodegradation of toluene by a lab-scale biofilter inoculated with Pseudomonas putida DK-1.

The biodegradation of toluene by biofiltration inoculated with Pseudomonas putida DK-1 was investigated with variation of the several environmental parameters, such as temperature, bed length, gas flow rate and optimal humidity zone. The optimal temperature range to treat toluene gas was found to be 32-35 degrees C. Increasing the gas flow rate showed an inverse effect on the elimination capacity and the removal efficiency. The optimal gas flow rate was obtained at 65 ml min(-1) from the relation between the removal efficiency and the elimination capacity. The biodegradation rate of the toluene with respect to the bed lengths (3, 6, 9, 12 and 15 cm) increased up to 80 h but was then independent of the bed lengths after 80 h except for the 3 cm bed length. The elimination capacity was improved by about 70% compared with that reported in other literature and was also in agreement with theoretical models.

Preparation of regular sized Ca-alginate microspheres using membrane emulsification method.

Monodisperse Ca-alginate microspheres were prepared using the membrane emulsification method. Three ionic types of drugs (anionic, cationic and non-ionic) were incorporated into the microspheres, and the effects of sodium alginate concentration and the pressure applied during the dispersing process on the properties of the microspheres were examined. Monodisperse microspheres were obtained when the concentration of alginate solution was 2 wt% and the pressure applied was 0.4 x 10(5) Pa. The mean size of microspheres was approximately 4 microm. Lidocaine x HCl (cationic), sodium salicylate (anionic) and 4-acetamidophenol (non-ionic) were selected as ionic model drugs and included in the alginate microspheres. Lidocaine x HCl (cationic drug) release was more retarded than that of the anionic drug, because of the electrostatic attraction between the negative charge of the ionized carboxyl group in the alginate chain and the positive charge of the cationic drug. In acidic release medium, a slow release was observed due to the low swelling characteristic and the increased viscosity of alginate, regardless of ionic type of drug.

Oxygen transfer characteristics in a pilot scale surface aeration vessel with Simcar aerator.

The volumetric mass transfer coefficient, KLa, was determined by dynamic method in a surface aerated pilot scale squared vessel up to 0.531 m3 equipped with Simcar type impeller. Through surface aeration, the oxygen transfer characteristics were investigated with the variations of operating variables such as stirring speed, impeller diameter, liquid height and power input per liquid volume (P0/V). It was seen from the results of different oxygen concentration absorption that the dynamic method might lead to errors in KLa when air was used for absorption. To provide reliable KLa values measured by dynamic, the KLa data using pure oxygen were used and confirmed with feeding steady-state method (FSM). As expected, KLa depends on P0/V, impeller size and liquid height. However, for Simcar type impeller, the KLa shows linear dependency on P0/V in contrast to majority of correlations reported in the literature which shows KLa variation of (P0/V)0.65 for disk type impeller. Moreover, it was interesting to find that the bubble behaviors inside the vessel computed by computational fluid dynamics (CFD) could explain qualitatively the KLa changes with operating variables. For the purpose of scale-up procedures, the empirical correlations for predicting KLa were developed within +/- 2% accuracy.

A novel pH-sensitive membrane from chitosan--TEOS IPN; preparation and its drug permeation characteristics.

A novel organic-inorganic composite membrane was prepared, using tetra ethyl ortho silicate (TEOS) as an inorganic material and chitosan as an organic compound. Equilibrium and oscillatory swelling studies were conducted to investigate swelling behaviors of the membrane according to the pH of the swelling medium. Drug permeation experiments were also performed in phosphate buffer solution of the pH of 2.5 and 7.5, respectively. Lidocaine HCl, sodium salicylate and 4-acetamidophenol were selected as model drugs to examine the effect of ionic property of drug on the permeation behavior. The effects of membrane composition and the external pH on the swelling and the drug permeation behavior of IPN membrane could be summarized as follows; chitosan incorporated into TEOS IPN swelled at pH 2.5 while shrunk at pH 7.5. This swelling behavior was completely reversible and the membrane responded rapidly to the change in environmental pH condition. According to swelling behavior, an increase in pH from 2.5 to 7.5 yielded an increase in the rate of drug permeation because of the shrinking of the incorporated chitosan in TEOS IPN, while decrease in pH resulted in low permeation rate. The optimal TEOS-chitosan ratio for maximum pH-sensitivity existed and drug permeation was influenced not only with the external pH but also with the ionic interactions between the drug and membrane.

Studies on the overall oxygen transfer rate and mixing time in pilot-scale surface aeration vessel.

An aerated vessel with Simcar type surface aerator was studied to estimate its significant performance characteristics i.e., oxygen transfer rate, mixing time and power consumption. The oxygen transfer and mixing characteristics were investigated with variations in the operating variables such as rotational speed, diameter, bottom clearance of impeller, liquid height and power consumption in single and dual impeller systems. The bottom clearance of the top impeller was found to affect largely the capacity of the impeller by varying the quantity of liquid loaded to it. It was also ensured that surface aeration caused a slight increase in mixing time compared to it under ungassed conditions. The dual impeller system was employed for the purpose of improving oxygen transfer and mixing at TH < 1 varying the types and the bottom clearance of thelower impeller. However, the oxygen transfer rate was independent of the lower impeller mainly depending on the capacity of the top impeller though mixing time was sharply reduced by the lower impeller. The effect of the bottom clearance of the lower impeller was related to the liquid flow pattern inside the vessel, which was presented by computational fluid dynamics (CFD). The oxygen transfer rate and the mixing time were correlated with power consumption within reliable error range.

Modeling of the Permeate Flux during Microfiltration of BSA-Adsorbed Microspheres in a Stirred Cell.

A study on the variation of the permeate flux was performed in a stirred cell charged with microspheres, to investigate the effects of the stirrer speeds (300, 400, and 600 rpm) and the BSA concentration (0.1, 0.2, 0.4, and 0.8 g/L) under constant pressure. The permeate flux increased over time before the saturation point, but it began to decrease after that point. An increase of the BSA concentration and the stirrer speed resulted in the rapid increase of the permeate flux. This is contrary to the observation of the conventional filtration experiments using a stirred cell. A resistance-in-series model was employed for the modeling of the permeate flux. The cake resistance (R(c), induced by the concentration polarization of microspheres) and the fouling resistance (R(f), induced by the adsorption of BSA inside the membrane pore) must be considered simultaneously for the modeling. These modeling results were in good agreement with the experimental data. These can be applied to the special system considering both R(c) and R(f) as well as the general filtration systems using a stirred cell. Copyright 2000 Academic Press.