Differential dependency on motion coherence in subregions of the human MT+ complex

The detection of coherent motion embedded in noise has been widely used as a measure of global visual motion processing. Animal studies have demonstrated that this performance is closely linked to the responses of direction-sensitive neurons in the macaque middle temporal (MT) and medial superior temporal (MST) areas. Despite the strong similarities between the visual cortex of human and that of non-human primates, the human middle temporal complex (area MT+), located in the posterior part of the inferior temporal sulcus and presumably comprising both area MT and area MST, has not consistently been found to share the functional hallmark of MT and MST neurons, i.e. their preference for coherent rather than incoherent visual motion. In order to search for such preferences in human area MT+, blood oxygen level-dependent responses to random dot kinematograms presented in the right visual hemifield were studied here as a function of stimulus size and dot density. The stimulus extensions were varied in such a way as to cover an area either equaling, exceeding or falling below the mean receptive field size of macaque area MT. Unlike the posterior part of human area MT+, the anterior part and its right-hemisphere homolog showed significantly stronger responses to coherent than to incoherent motion. These differences were only present for large stimuli that presumably exceeded the receptive field size of neurons in area MT. Our results suggest that functional magnetic resonance imaging may reveal stronger responses to coherent visual motion in human area MST, provided that the stimulus allows for sufficient summation within the receptive fields. In contrast, functional magnetic resonance imaging may fail to reveal the same dependency for human area MT.     

Solitary schwannoma of the glans penis

Schwannomas of the penis are extremely rare. A 69-year-old man presented with a circumscribed asymptomatic tumor on the dorsum of the glans penis. Histopathologic examination of the surgical specimen showed a benign schwannoma.     

Congenital coronary artery fistulas in adults: concomitant pathologies and treatment

Background Coronary artery fistula is a rare congenital malformation. Complications such as intracardiac shunts, endocarditis, myocardial infarction, aneurysm and sudden death can be observed. The purpose of this article is to present our experience with concomitant cardiac pathologies and discuss various therapeutic approaches including surgical and percutaneous intervention. Materials and methods During 18,272 diagnostic cardiac catheterizations, coronary artery fistulas were identified incidentally in 10 patients (0.05%). There were 3 female and 7 male patients. The patients’ ages ranged from 42 to 76 years. All patients with coronary artery fistula were preoperatively in New York Heart Association functional class and Canadian Cardiovascular Society class II or III. Results In addition to coronary artery fistula, coronary artery disease was detected in 4 patients (40%), a ventricular septal defect and an aneurysm of the sinuses of Valsalvae with aortic regurgitation in one patient (10%) and an anomalous origin of the LAD from the pulmonary trunk in one patient (10%) during cardiac catheterization. Four (40%) of the total of 10 patients had only coronary artery fistula. Surgical closure of the coronary artery fistula was performed in 7 patients (70%). An interventional fistula closure with a coil device was confirmed by cardiac catheterization in another 3 patients (30%). One patient of the latter group showed a small residual shunt from the LAD to the pulmonary trunk. No death or long-term morbidities could be observed. Conclusions Coronary artery fistulas are incidentally diagnosed during coronary artery angiographies in adults and should be closed to prevent complications.     

Automatic feature generation in endoscopic images

Motivation

Fiber optic endoscopy is essential for minimally invasive surgery, but endoscopic images are very challenging for computer vision algorithms, since they contain many effects like tissue deformations, specular reflections, smoke, variable illumination and field of view. We developed a method to extract features from endoscopic images usable for scene analysis and classification. These features could be used with data from other sensors for workflow analysis and recognition.

Materials and methods

Evolutionary reinforcement learning that automatically computes good features, making it possible to classify endoscopic images into their respective surgical phases. It is especially designed to abstract the relevant information from the highly noisy images automatically.

Results

Automatic feature extraction was used to classify images from endoscopic cholecystectomies into their respective surgical phases. These automatically computed features perform better than some classical features from computer vision. The automated feature extraction process enables reasonable classification rates for complex and difficult images where no good features are known.

Conclusion

We developed an automatic method that extracts features from images for use in classification. The method was applied to endoscopic images yielding promising results and demonstrating its feasibility under demanding conditions.     

Long-term outcome of endoscopic therapy in patients with bile duct injury after cholecystectomy

Background and Aim:  Bile duct lesions, including leaks and strictures, are immanent complications of open or laparoscopic cholecystectomy. Endoscopic procedures have gained increasing potential as the treatment of choice in the management of postoperative bile duct injuries.
Methods:  Between January 1996 and December 2006, 44 patients with biliary leakages and 12 patients with biliary strictures after cholecystectomy were identified by analyzing the endoscopic retrograde cholangiopancreatography database, clinical records, and cholangiograms. The long-term follow up of endoscopic treatment in biliary lesions after cholecystectomy was evaluated by this retrospective study.
Results:  In 34 of 35 patients (97%) with peripheral bile duct leakages, endoscopic therapy was successful. Transpapillary endoprothesis and/or nasobiliary drainage were removed after 31 (5–399) days. After stent removal, the median follow-up period was 81 (11–137) months. In patients with central bile duct leakages, the success rate after median 90 (4–145) days of endoscopic therapy was 66.7% (6/9 patients). The median follow up after stent removal in six successfully treated patients was 70 (48–92) months. Eleven of 12 patients (91.6%) with bile duct strictures had successfully completed stent therapy. The follow-up period of this patient group was 99 (53–140) months.
Conclusions:  Endoscopic treatment of bile duct lesions after cholecystectomy is effective, particularly in patients with peripheral bile duct leakages and bile duct strictures. Therefore, it should be the first-line therapy used in these patients. Although endoscopic management is less successful in patients with central bile duct leakages, an attempt is warranted.     

Histopathology studies in human malignant melanomas of the choroid after unsuccessful treatment with 106Ru/106Rh ophthalmic applicators

Choroidal malignant melanomas were examined after unsuccessful brachytherapy with ¹⁰⁶Ru/¹⁰⁶Rh ophthalmic plaques. The histologic findings were compared with those obtained in non-irradiated melanomas similar in size and location. Both groups revealed no significant clinical difference apart from the lower average age of the irradiated patients. Some of the histologic features (scar formation, changes in the distribution of cell types, rate of mitosis) represented reactions to irradiation. No single histologic feature was strongly correlated to the irradiated group. The phenomenon of radioinsensitivity observed in some malignant melanomas cannot be fully elucidated using conventional histologic methods.Offprint requests to: H. Klaus     

Lipopolysaccharides and leukotriene B4 induce independently regulated electrophysiological and immunological responses in cultured astrocytes

Astrocytes play an important role in immunological processes within the central nervous system. They are able to produce cytokines like interleukin 6 (IL-6) and depolarize substantially after stimulation stimulation by lipopolysaccharides (LPS) or leukotriene B₄ (LTB₄). Therefore, we investigated the coupling between these immunological and electrophysiological processes. Amiloride (250 μM), a blocker of various Na⁺ transport systems, inhibited LPS (5 μg/ml)-induced depolarization, whereas the LPS-induced release of IL-6 was unaffected, indicating different intracellular regulatory mechanisms. LTB₄ (1.0 μM) induced a depolarization of a similar degree but mediated by a different ionic mechanism and failed to induce a detectable IL-6 release. Dexamethasone (1.0 μM) and cycloheximide (2.0 μM) specifically reduced LTB₄-induced depolarization, while LPS-induced depolarization was unaffected, providing further evidence for different regulatory pathways. Neither the depolarization nor the immunological stimuli served as a proliferation signal. These data demonstrate that independent immunological and electrophysiological responses with specific intracellular regulation are evoked after stimulation with LPS or LTB₄. With respect to functional disturbance of depolarized glial cells, e.g. in maintaining local ionic homeostasis, neuronal excitability may be affected indirectly and by this way account for the apperance of neurological symptons during inflammatory CNS diseases.     

GABA and glutamate receptor development of cultured neurons from rat hippocampus, septal region, and neocortex

The early development of functionally active GABA and glutamate receptors on neurons from hippocampus, septal region, and neocortex of embryonic rats were studied using primary dissociated serum-free cell cultures. The responses to GABA and glutamate, applied to individual neurons by pressure ejection, were tested at different developmental stages, starting at 1 day in vitro (DIV) until 3 weeks. In all three types of neuronal cultures, the GABAA-receptor developed prior to the glutamate receptors, and after 9 DIV most of the neurons were sensitive to both GABA and glutamate. N-methyl-D-aspartate (NMDA) and non-NMDA receptor subtypes of the glutamate receptors could be distinguished in hippocampal cultures. The development of GABA and glutamate receptors on septal region neurons appeared to be delayed as compared to hippocampal neurons. In neocortical cultures the majority of neurons was sensitive to GABA just after plating, whereas the sensitivity to glutamate was retarded. The differences in GABA and glutamate receptor development among these three neuronal cultures provide evidence that the appearance of transmitter receptors on cultured neurons is predominantly determined by intrinsic mechanisms rather than by environmental conditions. The proportion of spontaneously active networks in these cultures increased with a time course very similar to the rise in glutamate-sensitive neurons suggesting that functional active glutamate receptors may be involved in the generation of spontaneous activity.