III-V nanowire arrays: growth and light interaction

Semiconductor nanowire arrays are reproducible and rational platforms for the realization of high performing designs of light emitting diodes and photovoltaic devices. In this paper we present an overview of the growth challenges of III-V nanowire arrays obtained by molecular beam epitaxy and the design of III-V nanowire arrays on silicon for solar cells. While InAs tends to grow in a relatively straightforward manner on patterned (111)Si substrates, GaAs nanowires remain more challenging; success depends on the cleaning steps, annealing procedure, pattern design and mask thickness. Nanowire arrays might also be used for next generation solar cells. We discuss the photonic effects derived from the vertical configuration of nanowires standing on a substrate and how these are beneficial for photovoltaics. Finally, due to the special interaction of light with standing nanowires we also show that the Raman scattering properties of standing nanowires are modified. This result is important for fundamental studies on the structural and functional properties of nanowires.

Enhancement of second harmonic signal in nanofabricated cones

Geometrical effects in optical nanostructures on nanoscale can lead to interesting phenomena such as inhibition of spontaneous emission,1,2 high-reflecting omnidirectional mirrors, structures that exhibit low-loss-waveguiding,3 and light confinement.4,5 Here, we demonstrate a similar concept of exploiting the geometrical effects on nanoscale through precisely fabricating lithium niobate (LiNbO3) nanocones arrays devices. We show a strong second harmonic generation (SHG) enhancement, shape and arrangement dependent, up to 4 times bigger than the bulk one. These devices allow below diffraction limited observation, being perfect platforms for single molecule fluorescence microscopy6 or single cell endoscopy.7 Nanocones create a confined illumination volume, devoid from blinking and bleaching, which can excite molecules in nanocones proximity. Illumination volume can be increased by combining the SH enhancement effect with plasmon resonances, excited thanks to a gold plasmonic shell deposited around the nanostructures. This results in a local further enhancement of the SH signal up to 20 times. The global SH enhancement can be rationally designed and tuned through the means of simulations.

Growth mechanisms and process window for InAs V-shaped nanoscale membranes on Si[001]

Organized growth of high aspect-ratio nanostructures such as membranes is interesting for opto-electronic and energy harvesting applications. Recently, we reported a new form of InAs nano-membranes grown on Si substrates with enhanced light scattering properties. In this paper we study how to tune the morphology of the membranes by changing the growth conditions. We examine the role of the V/III ratio, substrate temperature, mask opening size and inter-hole distances in determining the size and shape of the structures. Our results show that the nano-membranes form by a combination of the growth mechanisms of nanowires and the Stranski-Krastanov type of quantum dots: in analogy with nanowires, the length of the membranes strongly depends on the growth temperature and the V/III ratio; the inter-hole distance of the sample determines two different growth regimes: competitive growth for small distances and an independent regime for larger distances. Conversely, and similarly to quantum dots, the width of the nano-membranes increases with the growth temperature and does not exhibit dependence on the V/III ratio. These results constitute an important step towards achieving rational design of high aspect-ratio nanostructures.

Self-assembled quantum dots in a nanowire system for quantum photonics

Quantum dots embedded within nanowires represent one of the most promising technologies for applications in quantum photonics. Whereas the top-down fabrication of such structures remains a technological challenge, their bottom-up fabrication through self-assembly is a potentially more powerful strategy. However, present approaches often yield quantum dots with large optical linewidths, making reproducibility of their physical properties difficult. We present a versatile quantum-dot-in-nanowire system that reproducibly self-assembles in core-shell GaAs/AlGaAs nanowires. The quantum dots form at the apex of a GaAs/AlGaAs interface, are highly stable, and can be positioned with nanometre precision relative to the nanowire centre. Unusually, their emission is blue-shifted relative to the lowest energy continuum states of the GaAs core. Large-scale electronic structure calculations show that the origin of the optical transitions lies in quantum confinement due to Al-rich barriers. By emitting in the red and self-assembling on silicon substrates, these quantum dots could therefore become building blocks for solid-state lighting devices and third-generation solar cells.

Unexpected effects on arterial oxygenation during reduction in oxygen flow via a pumpless lung assist system

The authors describe the effect of marked increase in PaO2 in a patient with acute respiratory distress syndrome and treatment by a pumpless extracorporeal lung assist following reduction in oxygen sweep flow.

Spatially resolved Raman spectroscopy on indium-catalyzed core-shell germanium nanowires: size effects

The structure of indium-catalyzed germanium nanowires is investigated by atomic force microscopy, scanning confocal Raman spectroscopy and transmission electron microscopy. The nanowires are formed by a crystalline core and an amorphous shell. We find that the diameter of the crystalline core varies along the nanowire, down to few nanometers. Phonon confinement effects are observed in the regions where the crystalline region is the thinnest. The results are consistent with the thermally insulating behavior of the core-shell nanowires.

Clinical benefit of catumaxomab in malignant ascites in patient subpopulations in a pivotal phase II/III trial

e14000

Background: Parsons et al. (ASCO 2008) reported the results of a pivotal phase II/III trial in patients with malignant ascites due to epithelial cancer. Treatment with the trifunctional antibody catumaxomab resulted in a clinically relevant prolongation of puncture-free survival, defined as the time to the next therapeutic puncture or the time to death, whichever occurred first. Malignant ascites is a typical late-stage manifestation of cancer associated with a poor prognosis and survival. Effective treatment options are limited. It is thus of special interest if all patient subgroups derive objective benefit from treatment. Methods: A post-hoc analysis was performed on the 258 patients with epithelial tumors treated with catumaxomab + paracentesis or paracentesis alone (control) in the pivotal trial to investigate any association between the primary endpoint (puncture-free survival) and the primary tumor, metastases, or other prognostic parameters. Results: Puncture-free survival was lower in patients with non-ovarian vs ovarian tumors and those with a poor prognosis (metastases vs no metastases, elderly vs younger, or low vs serum protein level). However, there was always a statistically significant treatment effect for catumaxomab compared with the respective control group (p≤0.0001, log rank test, for all comparisons) (see table). Conclusion: Catumaxomab demonstrated a significant clinical benefit in patients with malignant ascites independent of the primary tumor or other prognostic factors. Therefore, catumaxomab could be considered as a treatment option for patients with a poor prognosis.

[Table: see text]

[Table: see text]

Safety of catumaxomab: Cytokine-release-related symptoms as a possible predictive factor for efficacy in a pivotal phase II/III trial in malignant ascites

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Background: As a targeted immunotherapy, the trifunctional antibody catumaxomab specifically binds to epithelial cell-adhesion molecule (EpCAM) on tumor cells and attracts T-cells via CD3 and accessory cells via its FcγRI/III+ region. The clinical relevance of this mode of action was demonstrated by Parsons et al. (ASCO 2008) in a pivotal phase II/III trial. Catumaxomab treatment resulted in a clinically relevant prolongation of puncture-free survival (defined as time to next puncture or time to death, which ever occurred first) in patients with malignant ascites. One of the most common adverse events associated with catumaxomab is cytokine-release-related-symptoms (CRRSs), which might be of predictive value for efficacy. Methods: The safety profile of catumaxomab was identified in the pivotal study. CRRSs (pyrexia, nausea, and vomiting) were among the most common adverse events in the catumaxomab group. A correlation between CRRSs and puncture-free survival, the primary endpoint, was performed to investigate whether patients who had CRRSs benefited from catumaxomab treatment more than those who had no CRRSs. Results: Among 157 patients, CRRSs were limited to the duration of catumaxomab treatment, with a median onset of 1 day after catumaxomab administration and a median duration of 1–2 days. Most of these symptoms were mild to moderate and were manageable by standard symptomatic treatment. Only 6 of 101 patients with CRRSs who were treated with concomitant medication required systemic corticoid therapy. Puncture-free survival was longer (48 days) in patients with (81%) CRRSs during catumaxomab treatment than in patients without (19%) CRRSs (27 days), although the difference was not statistically significant (p=0.1546, log rank test). Conclusions: CRRSs are a common occurrence with catumaxomab, due to its mode of action, during the treatment of patients with malignant ascites. Since CRRSs appear to be correlated with efficacy, they may therefore be a predictive factor for catumaxomab efficacy.

[Table: see text]

Peritoneal carcinomatosis immunotherapy with the trifunctional anti-EpCAM x anti-CD3 antibody catumaxomab in patients with colon, gastric, or pancreatic cancer: Long-term results after a 2-year follow-up

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Background: Peritoneal carcinomatosis (PC) from gastrointestinal (GI) cancer is associated with a poor outcome. The trifunctional antibody catumaxomab may induce remission by redirecting T-lymphocytes and Fcγ-receptor I/III positive accessory cells to tumor cells. The aim of this study was to investigate the treatment of PC with intraperitoneal catumaxomab. Methods: Patients with epithelial cell adhesion molecule (EpCAM)-positive PC from GI cancer were enrolled in a multicenter phase I study and received four sequential intraperitoneal catumaxomab infusions on days 0, 3, 7, and 10 at increasing doses. Results: Twenty-four patients were enrolled. The maximum tolerated dose (MTD) was reached at 10, 20, 50, and 200 μg on days 0, 3, 7, and 10, respectively. The most common drug-related adverse events at the MTD were fever, vomiting, abdominal pain, skin toxicity, and nausea. Eleven of 17 evaluable patients (65%) were progression-free at final examination: one patient had a complete response and three patients had a partial response. EpCAM-positive cells in peritoneal lavage samples decreased in six of 10 evaluable patients. Patient survival was compared in a post hoc matched-pair analysis with PC patients treated with conventional intravenous chemotherapy. Median survival from the time of diagnosis of PC was 502 days in study patients versus 180 days in control patients (log-rank p = .0083). Conclusions: Intraperitoneal treatment with catumaxomab had an acceptable safety profile. Elimination of tumor cells from peritoneal lavage samples, delayed disease progression, and prolonged survival indicate that intraperitoneal catumaxomab is a promising option for the treatment of PC from GI cancer.

[Table: see text]

[The way to establish laparoscopic donor nephrectomy as the method of choice in live kidney donation--a single centre experience]

INTRODUCTION

In contrast to the USA, laparoscopic donor nephrectomy is rarely practised in German transplant centres. Safety concerns and difficulties with the learning curve of this advanced laparoscopic procedure are the main obstacles to the establishment of this operation.

PATIENTS AND METHODS

From 1998-2005, we performed laparoscopic kidney procurement in 50 live kidney donors on an intention to treat basis harvesting a total of 29 left and 21 right kidneys for transplantation.

RESULTS

Negative adverse effects on the donor side were temporary nerve irritation (2 patients) and postoperative retroperitoneal hematoma. Reasons to convert to open nephrectomy were bleeding (2 patients) and adhesions (1 patient). On the recipient side, one kidney was lost due to renal vein thrombosis. Three patients required short-time dialysis after transplantation. All other kidney transplants worked without any problems.

CONCLUSION

Laparoscopic donor nephrectomy is a safe procedure and has been established as the method of choice for live kidney donation in our hospital.

Laparoscopic live donor nephrectomy for right kidneys: Experience in a German community hospital

BACKGROUND

Laparoscopic live donor nephrectomy has become the new gold standard for kidney procurement in many high-volume transplant centres worldwide, but it is often limited to left-sided donor kidneys. Concerns about adequate anatomical renal vessel length and sufficient surgical exposure are the main obstacles to the use of the laparoscopic approach for right kidney live donors as well.

MATERIAL AND METHODS

From 1998 to 2006 we performed laparoscopic kidney procurement in 73 live kidney donors on an intention-to-treat basis, harvesting a total of 48 left (LKG) and 25 right kidneys (RKG) for transplantation. We compared these two groups with respect to operating time, conversion rate, complications, hospital stay, and recipient outcome.

RESULTS

There were no differences in outcome of donor patients after left (D-LKG) or right laparoscopic donor nephrectomy (D-RKG). Operating time was 160 min in D-RKG versus 164 min in D-LKG. Warm ischemia was below 150 s in both groups. Hospital stay was 7.0 (D-RKG) versus 6.7 days (D-LKG). Negative events on the donor site were one temporary nerve irritation in each group and one postoperative retroperitoneal hematoma in the left kidney group. Reasons to convert to open nephrectomy were bleeding in two patients in the left kidney group and adhesions in one patient in the right kidney group. The outcome of the recipients after left (R-LKG) or right kidney (R-RKG) transplantation was similar. One kidney was lost due to renal vein thrombosis (R-LKG). Postoperative ureter complications occurred in one patient of each group. One patient of the R-RKG and two patients of the R-LKG required lymphocele fenestration. All other kidney transplants worked without problems.

CONCLUSION

Laparoscopic donor nephrectomy is a safe procedure and has been established as the method of choice for live kidney donation in our clinic. Laparoscopic procurement of right and left kidneys can be performed with comparable quality and outcome for donors and recipients.

Cell Cycle-Related Bystander Responses are not Increased with LET after Heavy-Ion Irradiation

Evidence has accumulated that irradiated cells affect their unirradiated neighbors, so that they in turn display cellular responses typically associated with direct radiation exposure. These responses are generally known as bystander effects. In this study, cell cycle-related bystander responses were investigated in three strains of human fibroblasts after exposure to densely ionizing radiation. Varying the linear energy transfer (LET) from 11 to 15,000 keV microm(-1) allowed a study of the impact of the complexity of DNA damage in the inducing cells on the responses of bystander cells. Using both broad-beam and microbeam irradiation, transient bystander responses were obtained for the induction of CDKN1A (p21). The latter was also observed when the transmission of bystander signals was limited to soluble factors. Targeted irradiation of single cells in confluent cell monolayers revealed no correlation between the amount of CDKN1A protein in the bystander cells and the radial distance to the targeted cells. In line with the induction of CDKN1A in bystander cells after irradiation with different LETs, a transient delay in the first G1 phase after irradiation of G0/G1 cells was observed. However, the CDKN1A induction revealed no significant effect on premature terminal differentiation considered to underlie fibrosis in irradiated tissue. Thus the unchanged differentiation pattern in bystander cells does not indicate pronounced, long-lasting effects.

A fast online hit verification method for the single ion hit system at GSI

For a single ion hit facility built to irradiate specific targets inside biological cells, it is necessary to prove that the ions hit the selected targets reliably because the ion hits usually cannot be seen. That ability is traditionally tested either indirectly by aiming at pre-etched tracks in a nuclear track detector or directly by making the ion tracks inside cells visible using a stain coupled to special proteins produced in response to ion hits. However, both methods are time consuming and hits can be verified only after the experiment. This means that targeting errors in the experiment cannot be corrected during the experiment. Therefore, we have developed a fast online hit verification method that measures the targeting accuracy electronically with a spatial resolution of +/-1 microm before cell irradiation takes place.

Influence of hospital volume on local recurrence and survival in a population sample of rectal cancer patients

AIMS

To investigate the role of hospital volume and individual hospitals on long term outcomes (local recurrence and survival) of rectal cancer patients.

METHODS

One thousand thirty-eight patients with rectal cancer were diagnosed between 1996 and 1998. From these, we analysed 884 patients with a resected invasive primary rectal cancer. Median follow-up was 5.7 years. The impact of hospital volume (<10, 10-30 and >30 rectal cancer patients annually) on local recurrence and survival was examined in a Cox model. Differences between the four largest clinics in the high volume group were also investigated.

RESULTS

In the multivariate model predicting survival the following variables were significant: UICC stage, grade, age, local recurrence, and (neo-) adjuvant therapy treatment. In the multivariate model predicting local recurrence UICC stage, tumour localisation, and neoadjuvant therapy treatment were significant variables. Hospital volume was not a significant factor for survival or local recurrence. Within the high volume category one hospital showed significantly worse local recurrence rates than all other hospitals, but no survival difference could be seen between the four largest hospitals of the high volume group.

CONCLUSIONS

This analysis of a rectal cancer population found that hospital volume did not determine survival or local recurrence. Detailed clinical data with long term follow-up from cancer registries are vital to demonstrate the quality of routine care.

Ambulantes Operieren in der Dermatologie

Outpatient surgery in dermatology is likely to become increasingly important in future, for a number of reasons. Current social legislation favors outpatient surgery, because hospitals must justify performing any procedure in the outpatient catalogue on an inpatient basis. The range of conditions being treated is also broadening, for example due to the growing popularity of aesthetic enhancement procedures. Epidemiological trends in skin cancer will also lead to considerable growth in demand for outpatient dermatological surgery. This article analyses current trends in ambulatory dermato-surgery, taking into account social, legislative, hygienic, legal and economic aspects. Measures to promote quality assurance are also described. The difficult cost situation facing outpatient surgery is creating a need for new forms of cooperation between primary care physicians and hospitals.

Prediction of gram-negative bacteremia in patients with cancer and febrile neutropenia by means of interleukin-8 levels in serum: targeting empirical monotherapy versus combination therapy

In a prospective observational study of 133 neutropenic episodes, interleukin (IL)-8 serum levels > 2000 pg/mL at the onset of fever had a sensitivity of 53% and a specificity of 97% as a predictor of gram-negative bacteremia (GNB; positive predictive value, 73%; negative predictive value, 94%). The rates of early death differed significantly between patients with high and those with low IL-8 levels (3/11 vs. 1/122; P< .01). Serum IL-8 levels at the onset of fever define a low-risk subgroup of patients who can safely be treated with monotherapy.

Dynamic contrast-enhanced MR angiography from the distal aorta to the ankle joint with a step-by-step technique

OBJECTIVE

The aim of this study was to visualize the arteries from the distal aorta to the ankle joint and to determine the accuracy of MR angiography for detecting stenoses and occlusions.

SUBJECTS AND METHODS

Twenty-four patients with peripheral arterial occlusive disease underwent digital subtraction angiography and were examined on a 1.5-T MR scanner. The transit time for contrast material was determined with a test bolus injection. A T1-weighted three-dimensional gradient-echo sequence with short TR and TE was used for a dynamic measurement at the level of the iliac arteries, the upper leg, and the lower leg arteries. For each level a single dose of gadolinium was injected into an antecubital vein with an MR power injector. Maximal-intensity-projection reconstructions were calculated after subtraction of the first measurement at each level. Two experienced MR radiologists who were unaware of the digital subtraction angiography results interactively evaluated both the MIP reconstructions and the single slices on a workstation, first independently and then in a consensus interpretation.

RESULTS

With digital subtraction angiography, 80 hemodynamically significant stenoses and 39 occlusions were detected. For the stenoses and occlusions, a sensitivity of 100% was found for MR angiography. The specificity for the assessment of stenoses and occlusions was 98% and 94%, respectively, for the iliac arteries; 98% and 94%, respectively, for the upper leg arteries; and 94% and 95%, respectively, for the lower leg arteries. Most false-positive findings of occlusion were due to metal stents present in the iliac (n = 3) and upper leg (n = 4) arteries.

CONCLUSION

The MR imaging technique that we used revealed the arteries from the distal aorta to the ankle and proved to be reliable at showing arterial stenoses and occlusions.

[Stenoses and occlusions of the supraaortic vessels--the interdisciplinary interventional treatment of patients with an increased surgical risk]

PURPOSE

The value of elective PTA in stenoses of the supraaortic vessels and especially of the carotid artery is still under discussion. Stenoses after surgical and/or radiation therapy and a high cardio-vascular risk for a surgical procedure, however, justify minimal-invasive techniques.

MATERIAL AND METHODS

In 31 patients with 24 symptomatic and 7 asymptomatic stenoses of the supraaortic arteries (3 Acc, 19 Aci, 5 Ascl, 4 Tr.brc, 2 Aax) minimal-invasive angioplasty and stent-placement was performed. The rationale for the interventional procedure was an elevated medical or technical risk of the respective surgical procedure. All procedures were performed using a coaxial technique with a guiding catheter. An open vascular access was necessary in 7 cases due to an unfavorable anatomical situation.

RESULTS

The technical success rate was 100%. Peri-interventionally, a TIA occurred in 2 patients (1 spontaneous relieve, 1 complete remission after rt-PA lysis therapy). During the mean follow-up period of 13 months 3 patients died due to non-cerebrovascular reasons. In 2 patients a moderate restenosis, in 1 a high-grade stenosis, and in 1 and complete occlusion occurred without symptoms. After one year of follow-up, all treated stenoses were patent with a restenosis rate of 10.7% without further neurological symptoms.

CONCLUSION

Interventional angioplasty with stent-placement of the supraaortic arteries is a safe and effective alternative in patients are at high risk for classical surgical procedures.

Myelodysplastic syndrome with monosomy 7 after immunosuppressive therapy in Behçet's disease

Only few cases of Behçet's and hematological malignancies have been reported until now. We recently observed a 39-year-old female patient with Behçet's disease developing a myelodysplastic syndrome (MDS) FAB subtype refractory anemia with excess of blasts in transformation [RAEB-t] with a monosomy 7 after being treated with cyclosporin A and chlorambucil for several years. This case is reported and the occurrence of hematological malignancies and Behçet's disease is reviewed.

Error-minimizing dead zone for basis function networks

The incorporation of dead zones in the error signal of basis function networks avoids the networks' overtraining and guarantees the convergence of the normalized least mean square (LMS) algorithm and related algorithms. A new so-called error-minimizing dead zone is presented providing the least a posteriori error out of the set of all convergence assuring dead zones. A general convergence proof is developed for LMS algorithms with dead zones, and the error-minimizing dead zone is derived from the resulting convergence condition. The performance is compared with the performance of classical dead zones.

[Therapy and prognosis in 360 laryngeal and hypopharyngeal cancers at the Erfurt ENT clinic 1978-1987]

We report 316 patients with carcinoma of the larynx and 44 patients with carcinoma of the hypopharynx. The 5-year survival rate for supraglottic carcinoma was 53%, for glottic carcinoma 74%, and for hypopharyngeal carcinoma 18%. The ratio of men to women was 17:1. The risk factors of chronic laryngitis, abuse of nicotine and alcohol are described.

Simultaneous demonstration of two antigens on single T cells using antibodies with contrasting labels

We describe a double labeling method for the discrimination of 2 antigens on single cells. It consists of a combination of 3H-immunoautoradiography and immunocytochemistry applied to cells previously fixed on poly-L-lysine (PLL)-coated multispot slides. The method has been applied to various mouse cells contemporaneously labeled with 2 different monoclonal antibodies. In order to distinguish the attached antibodies unambiguously, they were labeled with contrasting markers. One of the antibodies was marked with tritium blackening the photographic film that covers the slide. The other was detected with the peroxidase-anti-peroxidase (PAP) method forming a reddish precipitate. The contrast between the reddish reaction product of the PAP-labeled antibody and the black silver grains allows cells, specifically labeled with both antibodies, to be distinguished from cells labeled with only one or neither of the antibodies. Tritium-labeled antibodies were introduced because of their advantage over antibodies labeled with iodine in the closer localization of the silver grains to the bound antibody and their much longer halflife (60 days versus 12 years). In this study we applied a tritium-labeled anti-Thy-1.1 together with anti-Lyt-1 monoclonal antibody for studying the distribution of the corresponding antigens on lymphocytes in the mouse thymus and lymph node cells.