Der Einflu\ von Β-Sympathomimetika und sog. Ca++-antagonistischer Hemmstoffe auf den menschlichen Herzmuskel in vitro

Zusammenfassung Es wird erstmals im überlebenden fetalen Herzmuskel in der Gewebekultur über elektive Parenchymnekrosen durch überstimulation mit -Sympathomimetika berichtet. Das zur Langzeittokolyse verwendete Fenoterolhydrobromid induziert über ein von Fleckenstein beschriebenes pathogenetisches Prinzip Nekrosen einzelner Herzmuskelfasern in vitro. Fenoterolhydrobromid in Kombination mit einem Ca⁺⁺-Antagonisten verhindert über eine Verringerung des Ca⁺⁺-Einstroms in die Herzmuskelfaser sog. elektive Parenchymnekrosen. Diese Untersuchungsergebnisse zeigen, da\ elektive Herzmuskelfasernekrosen nicht nur coronarogen, sondern auch metabolisch in Szene gehen können.Für die ausgezeichnete technische Durchführung der Versuche danken wir M. Frick, E. Hufnagel (Gewebekultur), A. Tischendorf, S. Weisschedel, A. Mayer (Histologie und Foto), U.L. Kiesewetter (Elektronenmikroskopie)     

FMRI reveals functional cortex in a case of inconclusive Wada testing

OBJECTIVES: The intracarotid amobarbital test (Wada test) currently represents the gold standard for preoperative lateralization of hemispheric dominance. Here, we report an epileptic patient with a longstanding extended lesion of the left hemisphere showing absence of motor and speech dysfunction with left carotid amobarbital injection, but tetraplegia and speech arrest with right carotid injection interpreted as a neuroplastic shift of motor and language functions to the right hemisphere. In contrast to the Wada results, motor functional magnetic resonance imaging (fMRI) showed a strong left hemispheric activation with right hand movements. METHODS: Right and left hand motor fMRI was performed. FMRI results and neurophysiological information obtained by motor and sensory evoked potential measurements were compared with the Wada test results. RESULTS: Initial interpretation of neuroplastic shifts of intrinsic left hemisphere functions to the right brain was revised after fMRI results which were confirmed by motor and sensory evoked potentials. CONCLUSION: As motor inactivation usually is thought to be the most robust feature of the Wada test, this case demonstrates that fMRI may reveal residual functional cortex in cases of inconclusive Wada results.     

Investigations on regulation of HCG by cortisol (prednisolon) in trophoblast cells in vitro

OBJECTIVE: Trophoblast cells synthesize a variety of hormones, in which hCG plays a major role. On the strength of special enzymes they are capable of catalyzing the reaction cortisol <--> cortisone. In vitro experiments showed the influence on ACTH- and cortisol secretion by CRH, ACTH and prednisolon. In this study we describe the influence of cortisol (prednisolon) on hCG production of trophoblast cells in vitro. MATERIAL AND METHODS: Trophoblast cells were prepared from human term placentae by standard trypsin-DNAse dispersion of villous tissue followed by a percoll gradient centrifugation step. After adjusting the cell suspension to a defined cell concentration of 1 x 10 (6) cells/ml cells were cultivated. The addition of prednisolon followed every eight hours. The samples were collected after 24 hours for a total of 96 hours also from unstimulated cultures. Culture supernatants were assayed for hCG by enzyme-immunometric methods. RESULTS: The addition of prednisolon (50 microg/ml) stimulates the concentration of hCG in a time-depending manner. CONCLUSIONS: The trophoblast cell shows an increase in the concentration of hCG after stimulation with cortisol. For the first time an influence of cortisol (prednisolon) on hCG production could be demonstrated in cultured trophoblast cells.     

Neuronal apoptosis following human brain injury

Neuronal apoptosis has been investigated in paraffin-embedded brain tissue from 103 individuals who had sustained blunt head injury by use of the in situ nick translation (ISNT) technique. In order to provide reliable data for a forensic wound age estimation, a quantitative morphometric analysis was performed. Apoptotic neuronal cells could be detected in a cortical contusion with a wound age of 45 min at the earliest and in the majority of the cases with postinfliction intervals up to 2 weeks, numerous ISNT-positive cells were found adjacent to the traumatically injured area. The presented data indicate that neuronal apoptosis peaks at about 1 day and persists for at least 22 weeks after blunt head injury. The time-dependent occurrence of apoptotic cells can contribute to a forensic timing of cortical contusions and complements other immunohistochemical parameters, especially in the early postinfliction interval.     

Vestibular processing in human paramedian precuneus as shown by electrical cortical stimulation

The authors describe a 16-year-old patient with recurrent episodes of epileptic linear self-motion perception and occasional body tilts. Intracranial seizure monitoring located the seizure onset, caused by a circumscribed ependymoma, in the right paramedian precuneus. Electrical cortical stimulation of this area could reproduce the same vestibular sensations, which ceased after lesionectomy. The findings implicate the paramedian area of the precuneus in the processing of static and dynamic vestibular, probably otolithic, information.     

Extracellular calcium depletion as a mechanism of short-term synaptic depression

Recent experiments have demonstrated that normal neural activity can cause significant decrements in external calcium levels, and that these decrements mediate a form of short-term synaptic depression. These findings raise the possibility that certain forms of short-term synaptic depression at glutamatergic synapses throughout the mammalian CNS may be influenced by similar changes in external calcium. We use a computational model of the extracellular space, combined with experimental data on calcium consumption, to show that such short-term depression can be accounted for by changes in calcium just outside active synapses, provided that external calcium diffusion is restricted. Remarkably, the model suggests the novel possibility that synapses may possess private pools of external calcium that enforce some forms of short-term depression in a synapse-specific manner.     

20 alpha-Hydroxysteroid oxidoreductase activity and 20 alpha-dihydroprogesterone concentration in human placenta before and after parturition.

The objective of this investigation was to determine if decreased biosynthesis or increased catabolism of progesterone (P) during labor was responsible for the decreased concentration of hormone observed in the human placenta after labor and vaginal delivery. No significant difference was found in P biosynthesis by placental tissues examined before and after labor as evidenced by a similar activity of 3 beta-hydroxysteroid dehydrogenase: delta 5-isomerase. In contrast, there was a marked increase in P catabolism during labor, as shown by a significant (p less than 0.05) change in placental 20 alpha-hydroxysteroid oxidoreductase activity which increased from 835.5 +/- 103 (mean +/- SEM) pmoles of 20 alpha-dihydroprogesterone (20 alpha-DHP) generated per milligram of protein per hour before labor to 1,160.4 +/- 101 pmoles/mg/hr after labor. A similar significant (p less than 0.02) increase in enzyme activity was noticed in parallel assays of the reverse (20 alpha-DHP leads to P) reaction. As a consequence of increased P catabolism, placentas after labor had a 20 alpha-DHP concentration of 63.7 +/- 9.5 (mean +/- SEM) ng/mg protein, a value which was significantly (p less than 0.05) larger than that found before labor (37.8 +/- 8.3 ng/mg protein). These changes resulted in a modification of the placental tissue P/20 alpha-DHP ratio which decreased from 2/1 before to 1/1 after labor. The results indicate that the catabolism of P to 20 alpha-DHP increases significantly during human parturition. This phenomenon may be of importance in the mechanism of initiation and continuation of labor.