Biomedical subjects
Publications and source records attributed to W Becker.
The authors report on an orbital complication in a child of 14 years of age with an abscess on the upper eyelid and pansinusitis on the left side. The clinical suspicion of involvement of the orbita could be definitely clarified with computed tomography only. The article describes the regression of this finding.
Examples of localized brain edema and morphological changes, which are complications of late gestoses, are demonstrated by CT. Coordination and relation to clinical findings are discussed, involution by therapy is described.
A report is given on the diagnosis of obstructions of the ureter by means of computerized tomography, using 8 examples. We distinguish between exterior compression, stricture of the ureteral wall and intracanalicular blockage. Computerized tomography is indicated above all for external compressions on which anamnesis gives no information. The typical finding with CT is ectasis of the ureter above the stenotic region and structures with dense soft parts in the compression section, whereby the density pattern often gives hints as to the nature of the compression. However, benign genesis cannot always be distinguished from a malignant process.
A triple stomach in a 22 year old patient was evaluated by CT. In addition to the main stomach two cystic formations containing gastric mucosa were found. These accessory stomachs did not fill following ingestion of oral contrast medium. In the CT diagnosis of cystic masses of the upper abdomen multiple gastric formations should be considered.
The morphologic aspect of abdominal tuberculosis are evaluated by C.T. The necrotising tuberculosis of the genitourinary tract presents course cystic lesions of fluid density. Similar morphologic criteria are seen in ileocecal tuberculosis. The peritoneal tuberculosis is characterized by large soft tissue masses of a high density which can be found in nearly all areas of the abdomen. The increased morbidity of tuberculosis in people from foreign countries living in the Federal Republic of Germany is pointed out.
Neuronal responses to natural stimulation of neck proprioceptors were studied in the region of the small cell group x in the dorsolateral medullary brainstem of slightly anesthetized and paralyzed cats. Stimulation consisted of horizontal trunk rotations about C1 with the head fixed in space. Out of 74 neurons recorded, 92% showed an increase in discharge rate with ipsilateral neck stretch and a decrease with contralateral stretch (Type N I responses); 8% showed the reverse pattern (Type N II responses). In the primary head-to-trunk position, almost all neurons had tonic activity that probably stemmed from prestretched neck proprioceptors. Responses to sinusoidal stimulation and position trapezoids showed a static (position-sensitive) as well as a dynamic (essentially velocity-sensitive) component. The relative weight of the two components varied considerably among the neurons. It was not possible to distinguish discrete neuronal populations on the basis of the dynamic characteristics. There was no evidence of a convergent input from other receptor systems, such as the horizontal canal system. Several neurons responded to "muscle tapping" and showed an increase of the velocity component following systemic injection of succinylcholine. We take this as evidence that they may receive input from muscle spindle receptors.
Smooth pursuit and saccadic eye movements of schizophrenic patients were examined. In a pendulum (0.5 Hz) tracking task schizophrenic inpatients had a slightly lower smooth pursuit gain than outpatients and controls, who showed no significant differences. The number of saccades, counter-saccades and velocity arrests occurring in a 20 s tracking epoque was the same in patients and controls, but patients made larger saccades. When tracking a stepping target by saccadic eye movements, schizophrenic inpatients, and to a lesser extent outpatients, exhibited longer reaction times than controls and had a higher incidence of "non-fixation" (saccades away from the target while the target is stationary). Schizophrenic patients also showed a significantly larger proportion of dysmetric saccades (undershooting the target). While similar changes of reaction time and non-fixation score were observed in manic-depressives and alcoholics, dysmetria was more often found in schizophrenics and possibly constitutes the expression of a specific impairment of attention.
1. The elimination of dissolved free amino acids (FAA) by individual snails during a period of 2 hr was measured. The FAA concentration in the hemolymph and in the homogenate also was determined. 2. For uninfected, normally fed snails a daily FAA production of 0.7 +/- 0.25 mumol glycine equivalents/g live wt was found. With snails starving for 7 days the daily FAA release rate fell to a mean value of 0.44 +/- 0.19 mumol glycine equivalents/g live wt. Infection with Schistosoma mansoni, however, induced higher FAA loss with an average of 1.72 +/- 1.07 mumol glycine equivalents/g live wt/day. 3. The FAA concentration in the homogenate of both starved and infected B. glabrata was significantly reduced by comparison to the levels found for normally fed snails. 4. A clear drop in FAA concentration was found in the hemolymph of starved and infected snails, respectively. 5. The FAA concentrations in the hemolymph and the homogenate of parasite-bearing snails does not differ significantly from the results found for starved snails. By contrast, the FAA release of infected B. glabrata significantly increased in comparison to that of the starved snails.
A new biomechanical model using an external fixator is described, which produces physiological dynamic axial stresses on the long bones without causing harmful micromovements at the fracture site. The authors are of the opinion that their model will make it possible to stimulate fracture healing by influencing bone remodelling and tissue differentiation.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The present report considers goal directed human saccadic eye movements. It addresses the question how a given perceived target excentricity is transformed into the innervation pattern that creates the saccade to the target. More specifically, it investigates whether this pattern is an appropriately selected preprogram or whether it is continuously controlled by a local feedback loop that compares a non-visual eye position signal to the perceived target excentricity (a visual signal would be too slow). To this end, the relation between the accuracy of saccades aimed at a given target and their velocity and duration was examined. Duration and velocity were found to vary by as much as 60% while the amplitude showed no related variation and had an almost constant accuracy of about 90%. By administrating diazepam, the variabiity of saccade duration and velocity could be further increased, but still the amplitude remained almost constant. These results favour the hypothesis that saccadic innervation is controlled by a local feedback loop.
Kinesthetic information from labyrinthine and neck receptors is required for reflex control and conscious perception of posture and movement. This study considers (1) the neuronal responses to horizontal labyrinthine and neck stimulation and their interaction both in the anterior suprasylvian (AS) cortex and in the vestibular nuclei (VN) of cats, and (2) human turning sensation related to these stimuli. Convergence of labyrinthine (L) and neck (N) input of comparable sensitivity was found in 80% of the AS neurons and in only 27% of the VN neurons. At both sites, the on-direction of L-responses as well as N-responses was either to the ipsilateral or to the contralateral side (type I and type II responses, respectively). When combining the two stimuli during head rotation, the two inputs could be synergistic (same on-direction) or antagonistic (opposite on-directions). Their interaction consisted of either an additive or subtractive summation leading to enhanced or depressed interaction responses. These interaction patterns are compatible with the subtractive and additive mechanisms which have been proposed to be essential for the stabilisation of the trunk and of the head, respectively. The psychophysical experiments showed that human turning sensations depend on the part of the body to which they are referred. Subjects taking the trunk as reference, reported similar turning sensations during both labyrinthine and neck stimulation, and weak or no turning sensation during head rotation. This suggests an antagonistic interaction of the two inputs. In subjects taking the head as reference, neck stimulation induced an illusionary sensation of head turning. Its direction was such that it would be synergistic with the vestibularly induced sensation of head turning during isolated head rotation. Thus, there appear to exist parallels between the basic operations performed by neurons in cat and by human subjects during labyrinthine-neck interactions.
The present study provides evidence that during whole-body rotation and during isolated rotation of either the head or the trunk, essentially the same processing of labyrinthine and neck afferent inputs takes place in neurons of the cat's ASS cortex and in humans who try to distinguish these stimulus conditions. This processing includes, among others (1) measurement of angular velocity and displacement during labyrinthine stimulation (whole-body rotation); (2) indication of trunk rotation as well as of an apparent head rotation in the opposite direction during neck stimulation (isolated trunk rotation); and (3) subtraction as well as addition of labyrinthine and neck afferent inputs during combined stimulation (isolated head rotation). Subtraction provides a basis for the discrimination between whole-body rotation and isolated head rotation; addition may optimize the indication of movement and position of the head in space.
The accuracy of human goal-directed saccades during passive sinusoidal whole-body rotation is the same as that of normal saccades with the head still. Two mechanisms contribute to this accuracy: 1. There is an incomplete summation (70% on the average) of saccade and VOR velocities. 2. The duration of saccades during head rotation is lengthened if VOR and saccade velocities have the same direction, and is shortened if their direction is opposite. The latter finding supports the hypothesis that saccades are controlled by local feedback.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The inert gas SF6(Sulfur Hexa Fluoride) is resorbed very slowly by the middle ear mucosa. After insufflation of SF6 into the middle ear in cases of retraction of the tympanic membrane, respectively atelectasis, and in beginning adhesive processes after tympanoplasties, pathologic negative pressure, and the retraction of the tympanic membrane can be equalized for at least 6 weeks. A precondition for this treatment is an intact tympanic membrane besides the tube dysfunction. So a temporary tube dysfunction with all its negative effects to the middle ear can be bridged. In some cases this method is successful over a long period. In the other cases the gas insufflation with SF6 can be repeated. Also in the treatment of serous middle ear effusions in adults and in cases of tinnitus caused by middle ear diseases SF6 can be helpful.