Titanocene dichloride was capable of inhibiting the growth of different types of human tumors in vitro. A total of 14 patients with metastatic renal-cell carcinoma (RCC) received 270 mg/m2 titanocene dichloride every 3 weeks for 6 weeks. Although the toxicities and side effects encountered were mild to moderate, no partial or complete response was detectable. In conclusion, titanocene dichloride has no advantage in the therapy of RCC.
How features are attributed to objects is one of the most puzzling issues in the neurosciences. A deeply entrenched view is that features are perceived at the locations where they are presented. Here, we show that features in motion displays can be systematically attributed from one location to another although the elements possessing the features are invisible. Furthermore, features can be integrated across locations. Feature mislocalizations are usually treated as errors and limits of the visual system. On the contrary, we show that the nonretinotopic feature attributions, reported herein, follow rules of grouping precisely suggesting that they reflect a fundamental computational strategy and not errors of visual processing.
Perceptual decisions involve the accumulation of sensory evidence over time, a process that is corrupted by noise [1]. Here, we extend the decision-making framework to crossmodal research [2, 3] and the parallel processing of two distinct signals presented to different sensory modalities like vision and audition. Contrary to the widespread view that multisensory signals are integrated prior to a single decision [4-10], we show that evidence is accumulated for each signal separately and that consequent decisions are flexibly coupled by logical operations. We find that the strong correlation of response latencies from trial to trial is critical to explain the short latencies of multisensory decisions. Most critically, we show that increased noise in multisensory decisions is needed to explain the mean and the variability of response latencies. Precise knowledge of these key factors is fundamental for the study and understanding of parallel decision processes with multisensory signals.
The combined use of multisensory signals is often beneficial. Based on neuronal recordings in the superior colliculus of cats, three basic rules were formulated to describe the effectiveness of multisensory signals: the enhancement of neuronal responses to multisensory compared with unisensory signals is largest when signals occur at the same location ("spatial rule"), when signals are presented at the same time ("temporal rule"), and when signals are rather weak ("principle of inverse effectiveness"). These rules are also considered with respect to multisensory benefits as observed with behavioral measures, but do they capture these benefits best? To uncover the principles that rule benefits in multisensory behavior, we here investigated the classical redundant signal effect (RSE; i.e., the speedup of response times in multisensory compared with unisensory conditions) in humans. Based on theoretical considerations using probability summation, we derived two alternative principles to explain the effect. First, the "principle of congruent effectiveness" states that the benefit in multisensory behavior (here the speedup of response times) is largest when behavioral performance in corresponding unisensory conditions is similar. Second, the "variability rule" states that the benefit is largest when performance in corresponding unisensory conditions is unreliable. We then tested these predictions in two experiments, in which we manipulated the relative onset and the physical strength of distinct audiovisual signals. Our results, which are based on a systematic analysis of response time distributions, show that the RSE follows these principles very well, thereby providing compelling evidence in favor of probability summation as the underlying combination rule.
In human vision, the optics of the eye map neighboring points of the environment onto neighboring photoreceptors in the retina. This retinotopic encoding principle is preserved in the early visual areas. Under normal viewing conditions, due to the motion of objects and to eye movements, the retinotopic representation of the environment undergoes fast and drastic shifts. Yet, perceptually our environment appears stable suggesting the existence of non-retinotopic representations in addition to the well-known retinotopic ones. Here, we present a simple psychophysical test to determine whether a given visual process is accomplished in retino- or non-retinotopic coordinates. As examples, we show that visual search and motion perception can occur within a non-retinotopic frame of reference. These findings suggest that more mechanisms than previously thought operate non-retinotopically. Whether this is true for a given visual process can easily be found out with our “litmus test.”
Our study showed a positive effect of adjuvant chemotherapy and immunotherapy on decreasing tumor recurrence rate. No influence was observed concerning progression rate, which was low overall.
The human visual system computes features of moving objects with high precision despite the fact that these features can change or blend into each other in the retinotopic image. Very little is known about how the human brain accomplishes this complex feat. Using a Ternus-Pikler display, introduced by Gestalt psychologists about a century ago, we show that human observers can perceive features of moving objects at locations these features are not present. More importantly, our results indicate that these non-retinotopic feature attributions are not errors caused by the limitations of the perceptual system but follow rules of perceptual grouping. From a computational perspective, our data imply sophisticated real-time transformations of retinotopic relations in the visual cortex. Our results suggest that the human motion and form systems interact with each other to remap the retinotopic projection of the physical space in order to maintain the identity of moving objects in the perceptual space.
1. We have previously shown that among alpha 1-adrenoceptor antagonists used or investigated for the treatment of benign prostatic hyperplasia, tamsulosin discriminates alpha 1-adrenoceptor subtypes in rat tissues whereas alfuzosin and naftopidil do not. We now expand these studies to additional drugs (doxazosin, terazosin) being used and/or investigated for this purpose, and have evaluated all of these drugs at cloned subtypes and in human prostate. 2. Competition binding studies were performed with [3H]-prazosin in membrane samples from rat spleen, kidney and cerebral cortex and human prostate and with cloned alpha 1-adrenoceptors expressed in COS cells. Doxazosin and terazosin did not discriminate alpha 1-adrenoceptor subtypes in rat kidney and cerebral cortex. In contrast, the subtypes present in the tissues were well discriminated by the alpha 1A-adrenoceptor-selective reference drug WB 4101. 3. Alfuzosin, doxazosin, naftopidil and terazosin did not discriminate cloned alpha 1-adrenoceptor subtypes transiently expressed in COS cells whereas tamsulosin and WB 4101 did. 4. In human prostate, alfuzosin, doxazosin, naftopidil and terazosin did not discriminate the alpha 1-adrenoceptor subtypes present in this tissue whereas tamsulosin and the alpha 1A-adrenoceptor-selective reference drugs WB 4101, phentolamine and 5-methylurapidil did. Based on data with the alpha 1A-adrenoceptor-selective drugs, human prostate contains alpha 1A- and alpha 1B-adrenoceptors in an approximate 70:30% ratio. 5. We conclude that tamsulosin, in common with WB 4101, but in contrast to alfuzosin, doxazosin, naftopidil, and terazosin is selective for alpha 1A-adrenoceptors which appear to dominate in the human prostate; the therapeutic relevance of this selectivity remains to be assessed in clinical studies.
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