Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. I. Linear acceleration responses during off-vertical axis rotation

1. The dynamic properties of otolith-ocular reflexes elicited by sinusoidal linear acceleration along the three cardinal head axes were studied during off-vertical axis rotations in rhesus monkeys. As the head rotates in space at constant velocity about an off-vertical axis, otolith-ocular reflexes are elicited in response to the sinusoidally varying linear acceleration (gravity) components along the interaural, nasooccipital, or vertical head axis. Because the frequency of these sinusoidal stimuli is proportional to the velocity of rotation, rotation at low and moderately fast speeds allows the study of the mid-and low-frequency dynamics of these otolith-ocular reflexes. 2. Animals were rotated in complete darkness in the yaw, pitch, and roll planes at velocities ranging between 7.4 and 184 degrees/s. Accordingly, otolith-ocular reflexes (manifested as sinusoidal modulations in eye position and/or slow-phase eye velocity) were quantitatively studied for stimulus frequencies ranging between 0.02 and 0.51 Hz. During yaw and roll rotation, torsional, vertical, and horizontal slow-phase eye velocity was sinusoidally modulated as a function of head position. The amplitudes of these responses were symmetric for rotations in opposite directions. In contrast, mainly vertical slow-phase eye velocity was modulated during pitch rotation. This modulation was asymmetric for rotations in opposite direction. 3. Each of these response components in a given rotation plane could be associated with an otolith-ocular response vector whose sensitivity, temporal phase, and spatial orientation were estimated on the basis of the amplitude and phase of sinusoidal modulations during both directions of rotation. Based on this analysis, which was performed either for slow-phase eye velocity alone or for total eye excursion (including both slow and fast eye movements), two distinct response patterns were observed: 1) response vectors with pronounced dynamics and spatial/temporal properties that could be characterized as the low-frequency range of "translational" otolith-ocular reflexes; and 2) response vectors associated with an eye position modulation in phase with head position ("tilt" otolith-ocular reflexes). 4. The responses associated with two otolith-ocular vectors with pronounced dynamics consisted of horizontal eye movements evoked as a function of gravity along the interaural axis and vertical eye movements elicited as a function of gravity along the vertical head axis. Both responses were characterized by a slow-phase eye velocity sensitivity that increased three- to five-fold and large phase changes of approximately 100-180 degrees between 0.02 and 0.51 Hz. These dynamic properties could suggest nontraditional temporal processing in utriculoocular and sacculoocular pathways, possibly involving spatiotemporal otolith-ocular interactions. 5. The two otolith-ocular vectors associated with eye position responses in phase with head position (tilt otolith-ocular reflexes) consisted of torsional eye movements in response to gravity along the interaural axis, and vertical eye movements in response to gravity along the nasooccipital head axis. These otolith-ocular responses did not result from an otolithic effect on slow eye movements alone. Particularly at high frequencies (i.e., high speed rotations), saccades were responsible for most of the modulation of torsional and vertical eye position, which was relatively large (on average +/- 8-10 degrees/g) and remained independent of frequency. Such reflex dynamics can be simulated by a direct coupling of primary otolith afferent inputs to the oculomotor plant. (ABSTRACT TRUNCATED)     

The mechanism for nonspecific lipase from rat pancreas

Purified nonspecific lipase from rat pancreas appears to mediate the followin reaction sequence: (2) HE +nB in equilibrium HEBn; (2) HEBn + S inequilibrium HEBnS; (3) HEBnS IN EQUILIBRIUM EBnS' + ROH; (4) EBnS' + h2o vector HEBn + R'COO- + H+, where E equils enzyme, B equils bile salt, and S equils R'COOR. Evidence is presented for the occurrence, sequence and reversibility or irreversibility of the above four reactions. Also discussed are the activation energies for both a "good" and a "poor" substrate, the correlation between V and subsitituent function (o-) for a series of substituted benzoic acid esters, and the effects of steric hindrance. Studies of the incorporation of label from H2(18)O further detail the hydrolytic mechanism, and the effects of the physical state in which substrate is presented to the enzyme (micelles, emulsion, crude bulk phase, etc.) are discussed.     

Correlation between Negotiated Rents and Neighbourhood Quality: A Case Study of Two Cities in Sweden

The aim of this paper is to analyse whether or not differentiated rents reflect differences in neighbourhood quality in housing of similar quality and age in two target cities in Sweden. The system for rent setting in Sweden is partly based on a process of negotiation in which the annual change in actual rents is an outcome of negotiations between the local branch of the Swedish Union of Tenants and local municipal housing companies. One possible outcome of these negotiations could be change to the rental structure in the different neighbourhoods within the municipality. By allowing differences in negotiated rent outcomes in different neighbourhoods, a better relationship of rent level to tenant perception of neighbourhood quality can be achieved. It is the understanding of the authors that in a number of local-housing-market rent negotiations over the last decade, the parties involved have agreed on the need for and have consciously aimed towards making such adjustments. In this paper, regression analysis has been used to analyse data about rent levels for residential units from two cities in Sweden, namely Gothenburg and Luleå. It can be concluded that differentiated rents are indeed present, hence the existing rent-setting system in Sweden can be used to improve the relationship between rental structure and neighbourhood quality.     

Induction of swimming in the high spinal stingray by L-DOPA

Stingrays with high spinal transections, which do not spontaneously locomote, can be induced to swim by intravenous injection of L-DOPA. The L-DOPA-induced swim of the spinal animal is associated with patterns of EMG activity that appear similar to those of the spontaneous swim of the decerebrate preparation. However, in contrast to the decerebrate condition, the L-DOPA-induced cycles of swimming are slower and less vigorous. Furthermore, secondary periodicites and altered intersegmental timing relationships are also evident.     

A semi-structured clinical interview for the assessment of diagnosis and mental state in the elderly: the Geriatric Mental State Schedule. I. Development and reliability

A standardized, semi-structured interview for examining and recording the mental state in elderly subjects is described. It allows the classification of patients by symptom profile and can demonstrate changes in that profile over time. It is believed that good reliability is demonstrated between psychiatric raters both for psychiatric diagnosis made on the basis of the schedule findings and for individual items. The Geriatric Mental State Schedule (GMS) consists mainly of items from the eighth edition of the PSE (Wing et al. 1967), together with additional items from the PSS (Spitzer et al. 1964), and extra sections dealing with disorientation and other cognitive abnormalities. Modifications have been introduced to facilitate interviewing elderly subjects.     

Initial experiences with magnetic resonance endoscopy

BACKGROUND: In contrast to endorectal surface coils used to assess pelvic tumors, the magnetic resonance endoscope (MR) has all the features of a standard endoscope. In ex-vivo imaging of the porcine gastrointestinal tract, endoscopic MR demonstrates distinct histological layers of the gastrointestinal wall. The aim of this study was to assess the feasibility and the accuracy of endoscopic MR in local staging of patients with esophageal and rectal cancer. METHODS: From April to August 1996, 12 patients (5 female and 7 male, mean age 63 [range 44-84] years) with histologically proven esophageal (n = 6) and rectal (n = 6) cancer prospectively underwent endoscopic ultrasound (EUS) followed by endoscopic MR. The two radiologists reviewing the endoscopic MR images were blinded to the EUS results. Assessment of T and N stages was compared to EUS and histology. RESULTS: Endoscopic MR was well tolerated in all patients and there were no complications. Image quality was sufficient in 75%. Endoscopic MR T-staging correlated with EUS and histology in 7/12 and 5/7 patients respectively. Discordance was due to overstaging by endoscopic MR. N-staging correlated with EUS and histology in 10/12 and 6/8 cases respectively. Non-correlation was due to a number of false negative results at endoscopic MR. CONCLUSION: These early results demonstrate endoscopic MR to be feasible and to produce comparable local staging to EUS in patients with esophageal and rectal cancer. The ultimate goal will be to combine endoscopic MR with body coil MR imaging (for the assessment of distant metastases) in order to provide "one-step staging" for the entire evaluation of gastrointestinal tumors.