Neuroimaging in Pineal Tumors

BACKGROUND AND PURPOSE: The authors report radiological findings in 11 tumors in the pineal region, which were histologically diagnosed as germinomas, pineocytomas pineoblastomas, ependymomas, teratomas, and astrocytomas. METHODS: Computed tomography (CT) was performed in seven patients and magnetic resonance imaging (MRI) was performed in all patients. RESULTS: CT showed a solid or solid/cystic mass with variable contrast enhancement. MRI showed a heterogeneous mass, with hypointense signal on T1 and iso/hyperintense signal on T2-weighted images (WI) and gadolinium enhancement. Extension to adjacent structures occurred in five patients and spread through the cerebral spinal fluid (CSF) in two. CONCLUSIONS: Pineal region tumors have no pathognomonic imaging pattern. MRI and CT are complementary in diagnosis and are important to determine localization, extension, and meningeal spread.     

An evaluation of the existence of soluble suppressor factors in cloned antigen-specific T suppressor lymphocytes

The suppressive activity of two bovine serum albumin-specific class II-restricted T suppressor cell clones (BVI/5 and 83/2-D11) was compared to that of a feeder cell-independent, IL 2-dependent subline (HF1.IL-2) of an originally antigen-dependent class II-restricted Ts cell clone (HF1). No soluble suppressor factors can be found in BVI/5 and 83/2-D11 Ts cell extracts or culture supernatants under conditions where an unspecific factor can be derived from HF1.IL-2 cells. This factor, when isolated from cell extracts in the presence of n-octyl-beta-D-glycopyranoside, has a molecular weight of 70-80 kD. In absence of this non-ionic detergent, it has a high affinity to membrane fragments and is associated with a molecular weight of 300 kD or more. The data are discussed in connection with recent findings of direct T suppressor to T helper interaction by cell-cell contact.     

Effects of the new vagolytic compound ciclotropium bromide on heart rate and atrial vulnerability

The effects of the new vagolytic compound alpha-phenylcyclopentane-acetic acid-N-isopropyl-nortropine ester methobromide (ciclotropium bromide) on heart rate and atrial vulnerability were assessed in the animal experiment. Therefore, the comparative effects of atropine (A) and ciclotropium bromide (C) on heart rate (HR) and electrical stimulation thresholds for repetitive atrial extrasystoles (RET) and fibrillation (AFT) were established in 14 mongrel dogs (BW 20-30 kg, artificial ventilation, piritramide-N2O anaesthesia). AFT and RET were determined using trains of rectangular current pulses (13 single pulses, 2 ms, 200 Hz) applied to the right atrial endocardium via bipolar platinum electrodes during the vulnerable period of atrial excitation, which was determined by scanning of the relative refractory period in steps of 10 ms. A (0.025 mg/kg) caused a small transient increase in the AFT; HR rose from 82 +/- 7 to 138 +/- 10/min. Control values were regained after 30 min. RET did not show any significant change. C (0.25 mg/kg) effected a significant increase in the AFT from 7.7 +/- 2 to 34 +/- 6 mA and in HR from 93 +/- 5 to 148 +/- 6/min. The effects lasted about 2 h. RET was not altered.     

Changed visuomotor transformations during and after prolonged microgravity

A series of step-tracking experiments was conducted before, during, and after a 3-week space mission to assess the effects of prolonged microgravity on a non-postural motor-control task. In- and post-flight accuracy was affected only marginally. However, kinematic analyses revealed a considerable change in the underlying movement dynamics: too-small force and, thus, too-low velocity in the first part of the movements was mainly compensated by lengthening the deceleration phase of the primary movement, so that accuracy was regained at its end. The observed in-flight decrements in peak velocity and peak acceleration point to an underestimation of mass, in agreement with the re-interpretation hypothesis of Bock et. al. Post-flight no reversals of the in-flight changes (negative aftereffects) were found. Instead, there was a general slowing down, which could be due to post-flight physical exhaustion.     

Task-dependent mixtures of coordinate systems in visuomotor transformations

In two experiments the involvement of relative and fixed coordinate systems in visuomotor transformations was examined. The experimental task required the successive performance of two movements in each trial, which had to “correspond” to different visual stimuli. One kind of visual display indicated target positions by way of different horizontal positions of a vertical line on a monitor (position mode), while the other indicated movement amplitudes by way of different lengths of a horizontal line (amplitude mode). Formal analysis of variances and covariances of successive individual movements led to the conclusion that in the position mode visuomotor transformations were based on a mixture of relative and fixed coordinate systems, while in the amplitude mode only a relative coordinate system was involved. Thus, visuomotor transformations can be characterized as mixtures of different coordinate systems, and their respective weights in the mixtures are task-dependent. Received: 18 March 1997 / Accepted: 25 September 1997     

Plasticity of innervation of the medulla of axillary lymph nodes in the rat after antigenic stimulation

The purpose of this investigation was to test the hypothesis that activation of the immune system in rats will lead to changes in the density of innervation in lymph nodes. In order to reduce the variability between animals, the rats were reared under sterile conditions and immunostimulation was effected by subcutaneous application of bovine albumin in a region draining to the axillary lymph nodes of both sides. Control animals received an equivalent application of sterile physiological saline. The animals were sacrificed 10 days and 27 days and 4 months after immunostimulation. The nerves in the axillary lymph nodes were quantified by light microscopy in silver impregnated sections and at the ultrastructural level on ultrathin sections. The survival times were chosen so that the first group was in the ascending phase of antibody production, the second group at the peak, and the third group in the declining phase. Both at the light and ultrastructural levels, there were statistically significant differences in the density of innervation of medulla between the groups, with a particularly pronounced increase in the group 4 months after immunostimulation. At the ultrastructural level, there was also an increase in the density of incompletely ensheathed axonal profiles in the parenchyma of the medulla, while the nerves associated with blood vessels were not increased. We conclude that immunostimulation leads to morphological changes in the innervation of the medulla of axillary lymph nodes, that are consistent with the concept of functional activation of the autonomic nervous system through the immune system. © 1994 Wiley-Liss, Inc.