Wave onset in central gray matter - its intrinsic optical signal and phase transitions in extracellular polymers.

The brain is an excitable media in which excitation waves propagate at several scales of time and space. "One-dimensional" action potentials (millisecond scale) along the axon membrane, and spreading depression waves (seconds to minutes) at the three dimensions of the gray matter neuropil (complex of interacting membranes) are examples of excitation waves. In the retina, excitation waves have a prominent intrinsic optical signal (IOS). This optical signal is created by light scatter and has different components at the red and blue end of the spectrum. We could observe the wave onset in the retina, and measure the optical changes at the critical transition from quiescence to propagating wave. The results demonstrated the presence of fluctuations preceding propagation and suggested a phase transition. We have interpreted these results based on an extrapolation from Tasaki's experiments with action potentials and volume phase transitions of polymers. Thus, the scatter of red light appeared to be a volume phase transition in the extracellular matrix that was caused by the interactions between the cellular membrane cell coat and the extracellular sugar and protein complexes. If this hypothesis were correct, then forcing extracellular current flow should create a similar signal in another tissue, provided that this tissue was also transparent to light and with a similarly narrow extracellular space. This control tissue exists and it is the crystalline lens. We performed the experiments and confirmed the optical changes. Phase transitions in the extracellular polymers could be an important part of the long-range correlations found during wave propagation in central nervous tissue.

Concomitant bihemispheric cerebral ganglioglioma and hemangioma in an 18-month-old child: case report.

This is a rare case of concomitant bihemispheric cerebral ganglioglioma and hemangioma in an 18-month-old child. There were two identical processes; a combination of ganglioglioma and hemangioma was located in the parieto-occipital region of both cerebral hemispheres. The child underwent diagnostic computed tomographic and magnetic resonance imaging examinations for seizures and right-sided facial palsy, which showed the bilateral presence of parieto-occipital, oval, well-demarcated, subcortically located processes. A biparieto-occipital craniotomy was carried out and two well-demarcated abnormalities were observed and both were removed in toto. Two years after the operation, the boy had normal psychomotor development and remained free from seizures with no therapy required. Repeat magnetic resonance imaging showed no tumor recurrence. Gangliogliomas are relatively uncommon tumors in childhood, located in the supratentorial compartment and usually associated with seizures. Histopathologic and immunohistochemical analysis of the two processes found in our patient showed them to be a ganglioglioma and a hemangioma, confirming the dysontogenetic origin of these alterations and the association between malformations and tumor growth. The combination of ganglioglioma and hemangioma, especially bilateral presentation of two such identical processes in a young child, is very rare and was not found in the recent literature.

[Autologous corium-plasty in closure of muscle hernia. A case report]. / Die autologe Koriumplastik zum Muskelhernienverschluss. Ein Fallbericht.

The case involving a 33-year-old patient is presented who developed a muscle hernia through a fascia late defect subsequent to removal of internal fixation devices from the left femur. Because primary closure of the fascia could not be achieved, an autologous dermis graft harvested from the margin of the skin incision was used. A firm closure of the fascial gap was achieved and the patient has no complaints. Having used an autologous dermis graft, we were able to avoid an alloplastic substitute.