Search PubMed⌕ Search

Biomedical subjects

P Zieliński

Publications and source records attributed to P Zieliński.

6 recordsLinked to original sources
PubMed2005

Simple acoustic multiplexer.

Simple structures enabling the multiplexing of acoustic waves are presented. Such structures are constructed out of two monomode acoustic wires and two masses bound together, and to the wires by springs. We show analytically that these simple structures can transfer with selectivity and in one direction one acoustic wavelength from one wire to the other, leaving neighbor acoustic wavelengths unaffected. We give closed-form relations enabling to obtain the values of the relevant physical parameters for this multiplexing phenomena to happen at a chosen wavelength. Finally, we illustrate this general theory by an application.

Journal Article↗
PubMed2001

Virtual modelling of the surgical anatomy of the petrous bone.

The surgical anatomy of the petrous bone is difficult to learn and to imagine due to the porous structure. Obviously the surgeon's training is based on cadaver dissections as we are still lacking good, versatile models of the temporal bone and its important structures. The clearly visible, rapid development of computer science provides us with new possibilities that should be immediately engaged in modelling and simulating the human anatomy. The virtual, three-dimensional computer model of the bony pyramid was created based on the tomographic x-ray 1 mm slices and evaluated in accordance to its usefulness in learning and planning the neurosurgical approaches to the petrous region. The model was created in the virtual reality markup language, in order to make it available through the Internet. The basic anatomy of the main surgical approaches used in this region was visualised and evaluated in accordance with the real, intraoperative anatomy. The model could be easily accessed through the Internet. It was user-friendly and intuitive. The model seemed to be helpful in planning the basic approaches to the petroclival region. Computer science, with the help of the virtual modelling techniques, gives us a powerful method of learning and training surgical anatomy and approaches, although cadaveric dissection still remains the main point of the surgeon's training.

Computer Simulation↗
PubMed2000

Surgical anatomy of anterior petrosectomy.

Neurosurgical procedures in the region of the petroclival region of the skull base require unique knowledge of the local anatomy. The measurements of this region considering the visible anatomical landmarks are helpful both during surgery and while planning the general schemes for the approach. We have evaluated the anatomy of the anterior surface of the petrous bone and of the middle fossa taking into consideration the surgical removal of part of the petrous bone--the anterior petrosectomy. We have measured the distances and angles between the chosen structures in this region. The measurements were taken on 10 skulls, on both sides. The results enrich the algorithm of the anterior petrosectomy.

Adult↗
PubMed1999

Measurements of the Obersteiner-Redlich zone of the vagus nerve and their possible clinical applications.

The aim of our study was to describe anatomical variability of the root entry zone (REZ), also called the Obersteiner-Redlich zone, that represents the "junction zone" of glia and Schwann sheath of the cranial nerves. This zone has some clinical implications. The pulsatile compression of REZ by a vessel may produce clinical symptoms, such us trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia torticollis spasmodicus or even symptoms of essential hypertension when a vascular cross compression of REZ of a left vagus nerve is present. The vessel--cranial nerve contact in the skull base cysterns may be visualized in radiologic examinations, most accurately in magnetic resonance imaging. Because, we cannot distinguish the REZ from the rest of the vagus nerve in radiologic examinations we decided to measure the length of its REZ. The microanatomical study of the length of REZ zone of the vagus nerve was performed on 21 nerves taken from 17 human brain stems (12 men, 5 women, 14 left, 7 right), fixed with 8% buffered formalin solution. Paraffin embedded tissue was cut into 10-micron-thick sections parallel to the nerve longitudinal axis and stained with hematoxilin & eosin. Each of the nerves showed the presence of a zone of oligodendrocyte myelination, mean length 2 +/- 0.3 mm. In 17 nerves the transitional zone formed a cone-like process, in 4 nerves was shaped irregularly. The length of REZ (oligodendrocyte myelination plus "glial dome") had the mean length 3.5 +/- 0.9 mm.

Adult↗
PubMed1997

Remote effect of brain retraction on regional cerebral blood flow and cerebrovascular reserve on single photon emission computed tomography.

BACKGROUND: The purpose of this study is to evaluate the effect of brain retraction 1 year or more after intracranial aneurysm clipping, demonstrated by a regional cerebral blood flow (rCBF) imaging technique. METHODS AND RESULTS: rCBF and cerebrovascular reserve (CV) were evaluated in 40 patients 12-25 months after operation, using single photon emission computed tomography (SPECT) with Tc-99m-hexamethylpropylene amine oxime (HMPAO) combined with acetazolamide test. The images were analysed semiquantitatively, focusing on regions of interest (ROIs) chosen for places retracted during the operation. The regions of hypoperfusion in the retracted tissue were clearly visible in 26 cases. Assymmetry of measured activity, expressed in the Assymmetry Index, reached 12% (SEM +/- 8). After injection of acetazolamide during hypercapnia, the assymmetry decreased. CONCLUSIONS: The results confirm the negative role of brain retraction. However, these consequences seem to be diminished by good vasoreactivity.

Brain↗