Biomedical subjects
Publications and source records attributed to R Auer.
Anterior spina bifida or butterfly vertebral body has a well known and characteristic appearance on plain film and CT. Its appearance on magnetic resonance imaging also appears to be characteristic and should not be mistaken for more serious abnormalities.
Unilateral ablations of the motor cortex were performed on rats. One to two weeks following the ablation they were subjected to 30 min of reversible insulin-induced hypoglycemic coma. The levels of glutamate, aspartate, gamma-aminobutyric acid (GABA), taurine, adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and phosphocreatine (PCr) were determined in frozen tissue sections from the superior half of the caudate nucleus. The lesions induced a specific reduction in the levels of glutamate by approx. 10% in the dorsal caudate nucleus ipsilateral to the lesion, while no significant differences in the levels of aspartate, GABA, taurine, ATP, ADP, AMP or PCr were noted. Neuronal necrosis in the caudate nucleus in animals subjected to 30 min of insulin-induced hypoglycemic coma and one week recovery was assessed by light microscopy. Contralateral to the lesion, extensive neuronal necrosis, mainly affecting small and medium-sized neurons, was observed in the dorsal and lateral caudate nucleus. In the caudate ipsilateral to the lesion a complete amelioration of necrosis was noted in areas subjacent to the lesion. The data suggest that hypoglycemic brain damage is induced by excitotoxins such as glutamate or related compounds.
Neuronal necrosis in the brain resulting from status epilepticus of 15 to 120 minutes duration in ventilated and well-oxygenated rats was assessed. Seizures were induced by inhalation of the convulsant gas flurothyl, and terminated by withdrawal of flurothyl and a single injection of thiopental. The animals were allowed to recover for one week, and neuronal damage was assessed by cell counts following subserial sectioning of the brain and microscopical examination of the sections. Infarction of the pars reticulata of the substantia nigra occurred in 5 of the 6 animals with seizure duration of 30 minutes, and in all animals with longer seizure durations. There also was a common affectation of the central parts of the globus pallidus. The pars compacta of the substantia nigra was never affected. After 45 to 120 minutes of seizures, moderate neuronal necrosis was observed in the neocortex (layers 3 and 4), and after 60 to 120 minutes was seen in amygdaloid and thalamic nuclei, as well as in CA4 and CA1 hippocampal pyramidal cells. Notably, CA3 neurons were not damaged nor were dentate granule cells affected. After 120 minutes of seizures, damage regularly affected the neocortex and the ventral-posterior nuclei of the thalamus. A conspicuous feature was the localization of neuronal necrosis at sites close to the ventricles.
A detailed light- and electron-microscopic study of the damage to the rat dentate gyrus in hypoglycemia was undertaken, in view of the previously advanced hypothesis that hypoglycemic nerve cell injury is mediated by a released neurotoxin. The distribution of neuronal necrosis showed a relationship to the subarachnoid cisterns. Electron microscopy of the dentate granule cells and their apical dendrites revealed dendrosomal, axon-sparing neuronal pathology. Dentate granule cells were affected first in the dendrites in the outer layer of the stratum moleculare, sparing axons of passage and terminal boutons. Subsequently, the neuronal perikarya were affected, and Wallerian degeneration of axons followed. Cell membrane abnormalities preceded the appearance of mitochondrial flocculent densities and degradation of the cytoskeleton, and are suggested to be early lethal changes. The observed early dendrotoxic changes, and the dendrosomal, axon-sparing nature of the lesion implicate an excitotoxin-mediated neuronal necrosis in hypoglycemia.
A description is presented of a new flow-cytometer (FCM) computer system, the EPICS C analyzer, which was developed to be used by a moderately trained technician as opposed to an FCM expert. The system was made robust and user-friendly by the use of menu-based rather than command-driven software. The user primarily interacts with the self-explanatory menus by depressing one of the eight membrane selector switches located on each side of the screen. The minimizing of typing and restriction of the user's responses greatly simplify the use and design of the software. The EPICS C operates in two modes: as a reliable clinical instrument and as a research tool. The instrument settings are stored on disk files rather than manually logged into a book. The settings for the predefined tests are read from the disk.
The value of examining "polycystic disease" by means of nuclear medicine is being demonstrated -- using one case as an example. Nuclear medicine studies, because of their inherent capability of evaluating both morphology and function at the same time, seem to place this method ahead of others, including ultrasound and C.T.
Questionnaires concerning the type of oral examinations and preventive measures used in private practice were sent to 500 randomly selected dentists in the german-speaking part of Switzerland. 300 were returned completed, the majority of these anonymously. In the examination of new patients, bite-wing radiographs were the most commonly used diagnostic aid. This was reported in 60% of the offices--more often by younger than by older pracitioners, more frequently in urban than in rural offices and more often in surgeries treating less than 12 patients a day. Concerning oral restauration itself, the most frequently frequently reported procedures were the treatment of clinically visible carious lesions, polishing and the replacement of defective fillings. A broad spectrum of prophylactic oral hygiene aids were reported. Toothbrush and dental floss combined with oral hygiene instruction, however, were still the most commonly used. There was considerably correlation between the type of prophylactic acids used and the type of the dental practice. According to the questionnaires, fluoride prophylaxis is very regulary carried out and recommended. The ways in which this fluoride prophylaxis is carried out differs from practice to practice. Nutritional prophylaxis counseling was considered in the majority of the offices irrespective of the type of office. Relatively little emphasis was placed upon cooperation of the patient. From the questionnaries we calculated a need for about 550 DH for Switzerland. Younger dentists mentioned this need relatively moe often than older practitioners. A recall system was used in 70% of the practices, whereby annual and semi-annual intervals were reported with equal frequency. It is obvious that the emphasis placed upon prevention is not the same in all practices. This statement is valid also for the carious and periodontal diagnostic measures utilized. Much work as well as maybe a certain resignation resulting from previous failures may prevent the dentist from instituting more preventive measures in his practice. It is obvious that the graduates of the new dental hygiene school can help in this regard. However, because as yet these new graduates cannot supply even one half of the 550 required hygienists, it is discussed whether or not dental chair-side assistants with special training could motivate our patients toward a more satisfactory oral hygiene.
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Regarding schools, the first endeavours of preventive dentistry based on the results of modern scientific results were made in the early fifties in the Canton of St. Gall. Great efforts have been made since then and it is impossible to keep track of all activities. At the schools it is the teachers on one hand and specialized or lay auxiliary personnel on the other who organize and perform supervised toothbrushing exercises with fluorides. In Switzerland there are now some 30 full-time positions for auxiliaries charged with preventive measures at Kindergarten or school. An estimate of the population reached by the various methods of prevention is presented. The costs of prevention are but a small fraction of the cost of conservative treatment. In the majority of the private dental offices prevention is part of the activity, but with varying intensity. As to public clinics, the preventive programm run by the Volkszahnklinik Basel is most advanced. It is important that prevention is introduced in all regions of Switzerland and that it reaches the children of all ages. The future depends strongly on the availability of auxiliary personnel working at the schools and in the dental offices.