R2R-printed inverted OPV modules--towards arbitrary patterned designs

We describe the fabrication of roll-to-roll (R2R) printed organic photovoltaic (OPV) modules using gravure printing and rotary screen-printing processes. These two-dimensional printing techniques are differentiating factors from coated OPVs enabling the direct patterning of arbitrarily shaped and sized features into visual shapes and, increasing the freedom to connect the cells in modules. The inverted OPV structures comprise five layers that are either printed or patterned in an R2R printing process. We examined the rheological properties of the inks used and their relationship with the printability, the compatibility between the processed inks, and the morphology of the R2R-printed layers. We also evaluate the dimensional accuracy of the printed pattern, which is an important consideration in designing arbitrarily-shaped OPV structures. The photoactive layer and top electrode exhibited excellent cross-dimensional accuracy corresponding to the designed width. The transparent electron transport layer extended 300 µm beyond the designed values, whereas the hole transport layer shrank 100 µm. We also examined the repeatability of the R2R fabrication process when the active area of the module varied from 32.2 cm(2) to 96.5 cm(2). A thorough layer-by-layer optimization of the R2R printing processes resulted in realization of R2R-printed 96.5 cm(2) sized modules with a maximum power conversion efficiency of 2.1% (mean 1.8%) processed with high functionality.

Proangiogenic effects of ionizing irradiation on squamous cell carcinoma of the hypopharynx

OBJECTIVE

There is experimental evidence that ionizing irradiation affects a proangiogenic response. However, the relevance of this effect on tumour growth in vivo is not in detail investigated yet. The present objectives were to examine the influence of ionizing radiation on the expression of the vascular endothelial growth factor (VEGF) and its receptors (flt-1 and flk-1), the microvessel density and the tumour proliferation, in head and neck squamous cell carcinoma (HNSCC).

METHODS

We used a HNSCC-cell line, derived from a hypopharyngeal tumour, for subcutaneous injection in 16 athymic nude mice. After reaching an average diameter of 12-14 mm the xenografts were randomised and 8 out of the 16 animals (therapy group) were irradiated with a single fraction of 6 Gy while the control group remained without any intervention. The irradiated and the respective control tumours were prepared after 7 (T7) and 70 days (T70) for immunohistochemical analysis. The expression of VEGF, its receptors flk-1 and flt-1, the vessel density (CD31) and the proliferation rate (Ki67) were quantified.

RESULTS

At the point of time T7 we observed a reduction of the tumour growth rate, of the proliferative activity and of the VEGF- as well as of the VEGF-R-expression. At the point of time T70 we found increased values for proliferation, microvessel density, VEGF- and flk-1 expression in the therapy group compared to the therapy group at T7 as well as to the control group at T70.

CONCLUSION

These changes might suggest a long-term proangiogenic effect of irradiation, which might result in growth promotion of the remaining tumour after the end of therapy.

Evaluation of changes in central airway dimensions, lung area and mean lung density at paired inspiratory/expiratory high-resolution computed tomography

The aim of this study was to improve the understanding of interdependencies of dynamic changes in central airway dimensions, lung area and lung density on HRCT. The HRCT scans of 156 patients obtained at full inspiratory and expiratory position were evaluated retrospectively. Patients were divided into four groups according to lung function tests: normal subjects ( n=47); obstructive ( n=74); restrictive ( n=19); or mixed ventilatory impairment ( n=16). Mean lung density (MLD) was correlated with cross-sectional area of the lung (CSA(L)), cross-sectional area of the trachea (CSA(T)) and diameter of main-stem bronchi (D(B)). The CSA(L) was correlated with CSA(T) and D(B). MLD correlated with CSA(L) in normal subjects ( r=-0.66, p<0.0001) and patients with obstructive ( r=-0.62, p<0.0001), restrictive ( r=-0.83, p<0.0001) and mixed ventilatory impairment ( r=-0.86, p<0.0001). The MLD correlated with CSA(T) in the control group ( r=-0.50, p<0.0001) and in patients with obstructive lung impairment ( r-0.27, p<0.05). In patients with normal lung function a correlation between MLD and D(B) was found ( r=-0.52, p<0.0001). CSA(L) and CSA(T) correlated in the control group ( r=0.67, p<0.0001) and in patients with obstructive lung disease ( r=0.51, p<0.0001). The CSA(L) and D(B) correlated in the control group ( r=0.42, p<0.0001) and in patients with obstructive lung disease ( r=0.24, p<0.05). Correlations for patients with restrictive and mixed lung disease were constantly lower. Dependencies between central and peripheral airway dimensions and lung parenchyma are demonstrated by HRCT. Best correlations are observed in normal subjects and patients with obstructive lung disease. Based on these findings we postulate that the dependencies are the result of air-flow and pressure patterns.

Angiogenesis and fibroblast proliferation precede formation of recurrent tumors after radiation therapy in nude mice

Recently, the combination of ionizing radiation with inhibitors of angiogenesis has been reported to improve tumor eradication compared to treatment with irradiation alone. However, the mechanisms of this effect have not been defined. For this purpose [corrected] we established a non-small cell lung cancer model in nude mice. Tumor vascularization was visualized in vivo by MRI using gadolinium-DTPA as contrast agent. Further, cryosections were produced as close as possible to the MRI slice positions. Since we were interested in examining the formation of a recurrent tumor, irradiation was performed with a single fraction of 4 Gy. This dose caused a partial remission followed by recurrent tumor growth 25 to 35 days after therapy. The process of partial remission as well as formation of the recurrent tumor was examined in 28 nude mice analysing the following parameters: (i) contrast agent enhancement using high-resolution MRI, (ii) proliferation of tumor cells and fibroblasts using Ki-67 immunohistochemistry and (iii) formation of microvessels using CD31 immunohistochemistry. The latter analyses led to differentiation of three stages. Stage 1 (day 1 to day 15 after irradiation) was characterized by increasing areas of dead cell mass in hematoxylin-eosin-stained slides that corresponded to a decrease in tumor cell proliferation as well as contrast agent enhancement in MRI. The percentage of Ki-67-positive tumor cells decreased from initially 45.1% +/- 6.0% (mean +/- standard deviation) to 1.4% +/- 1.2% (mean +/- standard deviation) on day 15. Stage 2 (day 6 to day 20 after irradiation; overlapping with stage 1) was characterized by proliferation of fibroblasts leading to formation of fibrotic septae with abundant microvessels. Already during late stage 2, MRI identified new contrast agent enhancing areas. Stage 3 (day 20 to day 40 after irradiation) was characterized by new tumor cell proliferation. Interestingly, tumor cells almost exclusively proliferated in the direct neighbourhood of the fibrotic septae that had been formed in stage 2. Obviously, proliferation of fibroblasts and blood vessels was a condition prior to formation of recurrent tumor tissue. Thus, our results are in contrast with the view that tumors or recurrent tumors begin as avascular masses that later induce neovascularization. With respect to clinical practice, our results suggest that: (i) adjuvant anti-angiogenic therapy should not be limited to the day of irradiation but should cover a critical period until day 5 to day 20 after radiotherapy, (ii) adjuvant therapy should also include inhibition of fibroblast proliferation and (iii) MRI can identify a recurrent tumor 10 to 15 days before occurrence of new tumor growth.

Lack of mutagenic and co-mutagenic effects of magnetic fields during magnetic resonance imaging

Mutagenic and co-mutagenic effects of static, pulsed bipolar gradient, and high-frequency magnetic fields, as well as combinations of them, were examined using the Ames test. The Ames test using Salmonella typhimurium bacteria, wild-type strain RTA, preincubation assay, without metabolic activation, was performed. All combinations of magnetic fields were tested with and without co-exposure to N-methyl-N'-nitro-N-nitrosoguanidine and benzo[a]pyrene-4,5-oxide, ethylene oxide, carboplatin, or cisplatin. As expected, chemical mutagens caused a clear-cut increase of the revertants in the Ames test. However, neither the static fields nor a combination of a static magnetic field with the time-varying bipolar gradient field or a pulsed high-frequency magnetic field caused an alteration in the number of revertants in the Ames test. No co-mutagenic effect of any magnetic field combination was observed. In conclusion, magnetic fields used during clinical magnetic resonance imaging (MRI) were neither mutagenic nor co-mutagenic.

Focal airtrapping at expiratory high-resolution CT: comparison with pulmonary function tests

This study was undertaken to determine prevalence, extent, and severity of focal airtrapping at expiratory high-resolution CT, and to compare focal airtrapping with age, gender, pulmonary function tests, and blood gas analysis. Two-hundred seventeen patients with and without pulmonary disease underwent paired inspiratory/expiratory high-resolution CT. Six scan pairs with corresponding scan levels were visually assessed for focal--not diffuse--airtrapping using a four-point scale. Pulmonary function tests and blood gas analysis were available for correlation in all patients (mean interval 5 days). Focal airtrapping with lower lung predominance was observed in 80% of patients. Twenty-six of 26 patients with restrictive lung function impairment exhibited focal airtrapping (mean score 2.4), whereas only 72 of 98 (74%) patients with obstruction did (mean score 1.5; p < 0.05). Fifty-eight of 70 (83%) patients with normal lung function (mean score 1.8) and 19 of 23 (83%) patients with mixed impairment (mean score 1.8) had focal airtrapping. Focal airtrapping showed negative correlations with static lung volumes (-0.27 to -0.37; p < 0.001) in all patients and moderate positive correlations with dynamic parameters (0.3-0.4; p < 0.001) in patients with obstruction. No significant correlations were found with age, gender, and blood gas analysis. Visual assessment of focal--not diffuse--airtrapping at expiratory high-resolution CT does not correlate with physiological evidence of obstruction as derived from pulmonary function tests since the perception of focal airtrapping requires an adequate expiratory increase in lung density.

(3)He MRI in healthy volunteers: preliminary correlation with smoking history and lung volumes

MRI with hyperpolarized helium-3 ((3)He) provides high-resolution imaging of ventilated airspaces. The first aim of this (3)He-study was to compare observations of localized signal defects in healthy smokers and non-smokers. A second aim was to describe relationships between parameters of lung function, volume of inspired (3)He and signal-to-noise ratio. With Ethics Committee approval and informed consent, 12 healthy volunteers (seven smokers and five non-smokers) were studied. Imaging was performed in a 1.5 T scanner using a two-dimensional FLASH sequence at 30V transmitter amplitude (TR/TE/alpha = 11 ms/4.2 ms/<10 degrees ). Known amounts of (3)He were inhaled from a microprocessor-controlled delivery device and imaged during single breath-holds. Images were evaluated visually, and scored using a prospectively defined 'defect-index'. Signal-to-noise ratio of the images were correlated with localization, (3)He volumes and static lung volumes. Due to poor image quality studies of two smokers were not eligible for the evaluation. Smokers differed from non-smokers in total number and size of defects: the 'defect-index' of smokers ranged between 0.8 and 6.0 (median = 1.1), that of non-smokers between 0.1 and 0.8 (median = 0.4). Intraindividually, an anteroposterior gradient of signal-to-noise ratio was apparent. Signal-to-noise ratio correlated with the estimated amount of hyperpolarization administered (r = 0. 77), but not with static lung volumes. We conclude that (3)He MRI is a sensitive measure to detect regional abnormalities in the distribution of ventilation in clinically healthy persons with normal pulmonary function tests.

[Ultrafast MRI of lung ventilation using hyperpolarized helium-3]

OBJECTIVE

Assessment of the temporal and spatial dynamics of hyperpolarized Helium-3 (3He) distribution in the lung with ultrafast gradient-echo magnetic-resonance imaging.

MATERIAL AND METHODS

Coronal images of the lung were acquired using ultrafast gradient-echo pulse sequences with TR/TE = 3.3 ms/1.3 ms (slice thickness, 40 mm) and TR/TE = 2.0 ms/0.7 ms (without slice selection). A series of 80 or 160 projection images was obtained with 210 ms or 130 ms temporal resolution, respectively. Imaging was performed during several respiratory cycles after application of a single bolus of 300 mL hyperpolarized 3He. Measurements were performed in six healthy volunteers (spontaneous breathing).

RESULTS

Different phases of in- and expiration could be visualized. During the course of consecutive respiratory cycles the 3He signal decreased due to dilution of 3He in residual alveolar gas and by inspired air, relaxation due to oxygen and the RF pulses, and due to Helium-3 washout. The signal of a single bolus of 3He was detected in the lung for up to four respiratory cycles. Anatomical structures were better visualized on slice selective images than on images without slice selection.

CONCLUSION

Distribution of inspired 3He within the tracheobronchial tree and alveolar space and its washout can be visualized by ultrafast imaging of a single bolus of hyperpolarized 3He gas. This method may allow for regional analysis of lung function with temporal and spatial resolution superior to conventional methods.

[Value of spirometry-gated high resolution computerized tomography of the lung during inspiration and expiration]

PURPOSE

To compare mean lung density (MLD) of paired inspiratory and expiratory thin-section CT scans acquired after patient instruction or using spirometric gating.

MATERIALS AND METHODS

21 patients (13 m, 8 f. median age 59 years, two with normal lung function, 15 with obstructive, 4 with restrictive impairment) underwent thin-section CT. Paired inspiratory and expiratory scans were performed in the upper, middle and lower lung fields. They were acquired after automatic patient instruction with constant intervals between instruction and scan. Spirometrically gated scans were acquired within 4 days at 80% and 20% of vital capacity (VC) which has been determined on the CT scanner in supine position directly prior to the examination using the built-in spirometric option. Semiautomatic segmentation of the lung was performed and MLD was calculated. VC of pulmonary function testing was available for correlation.

RESULTS

Inspiratory MLD was -828 +/- 71 HU with spirometric gating and -818 +/- 87 HU without. Expiratory MLD was -750 +/- 119 HU (increase 78 +/- 58 HU) with spirometric gating and -748 +/- 119 HU (increase 70 +/- 46 HU) without. All differences were non-significant. Intraindividual differences were 10 +/- 21 HU for inspiration and 2 +/- 36 HU for expiration. VC under CT-conditions was significantly smaller than that known from pulmonary function tests (1.9 +/- 0.71 vs. 2.7 +/- 0.81, p < 0.005).

CONCLUSION

Spirometric gating does not lead to different results for MLD as compared with acquisition of paired inspiratory and expiratory thin-section CT after automatic patient instruction.

Ruptured mature cystic teratoma of the ovary with recurrence in the liver and colon 17 years later. A case report

A mature cystic teratoma of the ovary occurred in a 51-year-old woman and recurred as a large intrahepatic tumor mass as well as a small mass in the transverse colon 17 years after rupture, intraperitoneal spillage of tumor contents and subtotal surgical removal of the ovarian lesion and peritoneal implants. The patient was treated with a partial hepatectomy and a segmental transverse colectomy. The recurrent lesions, which contained histologically fully mature teratomatous elements only, were excised; the result was a complete cure. To our knowledge this is the first documented report on such a complication of mature cystic teratoma of the ovary.

Comparison of three nonsurgical treatments for bleeding esophageal varices

Ninety-seven patients with recent or active variceal bleeding were randomly assigned to oral propranolol, endoscopic sclerotherapy plus oral propranolol, or transhepatic sclerotherapy plus oral propranolol. The effects of treatment on the number of units transfused, rebleeding of any magnitude, major rebleeding, and death were assessed in these patients, 82% of whom were alcoholic and 81% Child's Class C. After a minimum follow-up interval of 2 yr (range, 27-65 mo), major rebleeding rates were 65% for propranolol alone, 45% for endoscopic sclerotherapy plus propranolol, and 60% for transhepatic sclerotherapy plus propranolol. The corresponding death rates were 81% for propranolol alone, 55% for endoscopic sclerotherapy plus propranolol, and 66% for transhepatic sclerotherapy plus propranolol (p = 0.03). Thirty-three patients (34%) never received propranolol; 8 due to medical contraindications and 25 because they died or bled enough to meet the definition of treatment failure within 3 or 4 days of randomizations (no significant differences among treatment groups). Patients assigned to propranolol alone bled sooner, bled more units, and had a higher mortality rate than patients treated by endoscopic sclerotherapy plus propranolol. Patients treated with transhepatic sclerotherapy plus propranolol had intermediate results. Propranolol alone is inadequate treatment for esophageal variceal bleeding in patients with advanced liver disease.

A study of optimal length of flexible fiberoptic sigmoidoscopes for initial endoscopic training

Eighteen trainees with no prior fiberoptic endoscopic experience performed a total of 305 fiberoptic sigmoidoscopies using a colonoscope. Basic training, consisting of reading materials, lecture instructions, practice on a colon model, and observation of procedures, was completed prior to beginning patient examinations. Additional instruction was given between examinations. The performance of these examinations was an individual effort on the part of the trainee without verbal or mechanical assistance from the instructor after the initial ten examinations. All were performed with an instructor viewing through a teaching attachment. Total insertion distance was greater than or equal to 30, greater than or equal to 40, greater than or equal to 50, greater than or equal to 60 cm in 65, 60, 46, and 20 percent of examinations, respectively. Overall performance was better in those with prior rigid sigmoidoscopic experience (20 examinations). The mean examination time was 11.8 minutes. These data help to define the appropriate length of fiberoptic sigmoidoscope recommended for use by inexperienced endoscopists.

Training resident physicians in fiberoptic sigmoidoscopy. How many supervised examinations are required to achieve competence?

Twenty-five resident physicians performed 495 fiberoptic sigmoidoscopic examinations that were graded for overall skill according to a six-point competence scale. In general, 24 to 30 examinations were required to become competent at fiberoptic sigmoidoscopy. Trainees with prior rigid sigmoidoscopy experience achieved competence more quickly than those with no prior rigid sigmoidoscopy experience. As experience increased, unassisted insertion distance and luminal visualization increased, insertion time and assisted time decreased, and management scores and percent correct diagnoses improved. Trainees detected 93 to 100 percent of polyps and cancers viewed by the experienced sigmoidoscopist once competence was achieved. These data indicate that programs for training primary care physicians in fiberoptic sigmoidoscopy are feasible, help define the number of examinations required to become competent, and indicate that such trainees should be effective in cancer screening.