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Biomedical subjects

I Melichar

Publications and source records attributed to I Melichar.

At least 19 recordsLinked to original sources
PubMed2006

[Arthroscopic management of traumatic luxation of the patella].

AIM: The authors present a restrospective assessment of acute traumatic patellar luxation. MATERIAL: From 1999 to 2003, the authors treated 57 patients with acute traumatic patellar luxations, including 36 females and 21 males, the age range was 16-40 years. In cases of marked lateralization of the patella, the injured medial retinaculum was sutured under arthroscopic control. Furthermore, should the lateralization persist, lateral release of the patella was conducted. Early patellar cartillage injuries were detected in 34 subjects (59%), injuries of the lateral femoral condyle in 19 subjects (33 %). Patellar chondromalacia, grade 1-2 was diagnosed in 16 subjects. Free cartillagenous particles within the joint were detected in 18 subjects. Reconstruction of the cartillage was conducted in extensive injuries in 13 subjects. RESULTS: The subjects were assessed 1-4 years after the injuries and surgery. In one case (2%), a relaps of the patellar luxation, due to a new contact sport injury (a direct impact), was recorded. Assessment results, using the Lysholm score, were defined as follows: 93%-excellent and good, 7% fair. CONCLUSION: Sparing surgical techniques, followed by appropriate rehabilitation care, may optimalize the healing process of the injured tissue and prevent relapses of patellar luxations, as well as further wearing of femoropatellar cartillages.

Adolescent↗
PubMed1999

[The compartment syndrome in injuries of the upper extremity in children].

In the Centre for Child Traumatology in Brno the authors followed up during the last 10 years 22 patients with suspected compartment syndrome of the upper extremity. Incisions of intrafascial spaces were made in 12 patients-9x on the forearm and 3x on the hand. Another 10 patients had conservative treatment. The therapeutic results are with the exception of one female patient with developed Volkmann's contracture very satisfactory, the sequelae are only cosmetic. Compartment syndrome is a serious acute condition in child traumatology. Permanent sequelae of this syndrome can be prevented above all by early diagnosis and adequate therapy. It is therefore important to consider the possible development of this serious complication.

Arm Injuries↗
PubMed1999

[The compartment syndrome in injuries of the lower extremity in children].

A total of 22 patients with suspected compartment syndrome in the lower extremity were treated over the period of the last ten years at the Paediatric Traumatological Centre in Brno. CS was confirmed in 15 cases of these patients and incisions of intrafascial areas were performed in the course of treatment, 13 times on the middle leg and twice on the thigh. A conservative procedure was selected in 6 cases when diagnosis was not clearly confirmed: twice on the foot and 4 times on the middle leg. In diagnostics and treatment we definitely prefer permanent monitoring of intrafascial pressures and performance of adequate fasciotomies. Therapeutic results revealed to be good in implementing a correct procedure. Prevention of the iatrogenic ratio of this serious syndrome caused particularly by late assessment of diagnosis is important.

Child↗
PubMed1999

[Treatment of fractures in the elbow region in children using the Fragment Fixation System--initial experience].

In child traumatology among implants an irreplaceable place is held by Kirschner wires. An improved version of this implant is the Orthofix Fragment Fixation System (FFS) of Kendall Co. which combines the advantages of Kirschner wires with the compressive properties of a screw. During the past two years at the Clinic of Child Surgery and Traumatology in Brno by osteosynthesis, using FFS implants, a total of 21 patients were treated incl. 19 under the age of 15 years. On account of injuries of the elbow 15 children were treated (radial physis of the humerus--9x, ulnar epicondyle--4x, fracture of the ulnar olecranon--2x). The authors present an account of the hitherto assembled favourable experience and results of this method in the treatment of injuries of the elbow in children.

Adolescent↗
PubMed1996

[Personal experience with elastic stable intramedullary osteosynthesis in children].

Derived from Ender's elastic nail and from other fixation techniques, elastic stable intramedullary nailing (ESIN) provides a combination of elastic mobility and stability. The operation uses only small incisions, is rapid, blood loos is minimal and physeal area stands intact. Mobilisation using crutches but without-bearing is allowed as soon as the fracture is painfree and from third week starts partial weight-bearing. Between November 1994 and May 1996 21 children with femoral shaft fracture, 7 children with tibial shaft fracture and 1 child with humeral shaft fracture were admitted to the Pediatric Hospital in Brno and treated with ESIN. The guider and the nails from finest quality steel were made for us by the czech firm Medin, a. s. to order. We report about our good experiences with the ESIN-method.

Child↗
PubMed1992

Characterization of marginal and Claudius' cells growing from cochlear explants in vitro.

Tissue specimens of stria vascularis together with spiral ligament were transferred from the guinea pig cochlea to tissue culture dishes. To characterize and identify cells growing out from the explants, indirect immunofluorescence microscopy was used. The expression of the intermediate-sized filaments vimentin and cytokeratin 18 in cells on the surface of tissue specimens and in cells growing out from the explants after different cultivation periods were compared. Basically, three types of cells grew from the explants during several days: marginal cells, Claudius' cells and fibroblast-like cells. In primary cultures of explants, growth of marginal cells was observed in 25% of the dishes. Their proliferative activity, estimated by the use of the BrdUrd-DNA antibody, started in the stria vascularis and continued across the attachment of Reissner's membrane down to the bottom of the cell culture dish. The newly-formed marginal cells expressed cytokeratin 18 in the same way that original marginal cells on the tissue specimen do. If the newly-formed marginal cells were in contact with fibroblast-like cells or were forming groups (domes) on the bottom, they expressed vimentin. In 3% of the dishes growth of Claudius' cells was observed. Proliferative activity of these cells was found at the point where the basilar membrane was attached to the spiral ligament. New Claudius' cells spread at the opposite side of an explant when compared with the location of new marginal cells. Original as well as newly-formed Claudius' cells contained cytokeratin 18. Fibroblast-like cells were commonly present in cultures and contained only vimentin.

Animals↗
PubMed1992

Ultrastructure of cultured marginal cells of the guinea pig cochlea.

Explants of stria vascularis and spiral ligament of guinea pig cochlea were kept in primary culture. On the explant, proliferating marginal cells advanced by 15 microns/day, suggesting that in vivo defects of the strial epithelium can be covered by new marginal cells. The marginal cells growing in the cell culture dish had a diameter of 12.8 +/- 0.7 microns and formed an epithelial monolayer. Adjacent cells were connected by desmosomes and tight junctions. The cells were uniformly polarized. The apical membrane had small invaginations and numerous microvillus-like extensions, and the convoluted lateral membrane interdigitated with adjacent cells. The basal infoldings were smaller in cultured cells than in vivo; mitochondria were dispersed in the entire cytoplasm rather than concentrated in basolateral infoldings. The basal membrane infoldings of cultured marginal cells did not interdigitate with underlying fibroblast-like cells. Marginal cells were separated from underlying fibroblast-like cells by a fluid-filled space which was sometimes enlarged, leading to the formation of "domes" in the otherwise planar epithelium.

Animals↗
PubMed1991

Primary culture of vital marginal cells from cochlear explants of the stria vascularis.

Explants of the stria vascularis and spiral ligament were dissected from guinea pig cochleae and were successfully cultivated for several weeks. After 2 days, fibroblast-like cells of the spiral ligament covered the bottom of the cell culture dish around the explant. Marginal cells of the stria vascularis proliferated and grew on the luminal surface towards the border of the explant at a rate of 15 microns/day. At day 6 in culture the proliferating marginal cells reached the border of the explant and then advanced to the bottom of the cell-culture dish. There the marginal cells replaced fibroblast-like cells and built an epithelial hexagonal-shaped monolayer. Light microscopic and transmission electron microscopic investigations revealed that the cultured cells were viable and that typical morphological characteristics of marginal cells were preserved. Cultivation of these cells provides a unique model for studies of physiological properties of marginal cells of the stria vascularis.

Acridine Orange↗
PubMed1990

Deterioration of hearing function in mice with neural crest defect.

Cochlear potentials were recorded in black-eyed white-mutant mice (strains W/Wv and S1/S1d) during the first months of postnatal life. In these animals melanocytes from the neural crest do not reach the stria vascularis. Hearing thresholds indicated by the compound action potential of the auditory nerve progressively increased. Hearing loss in comparison with the control CBA mice amounted 40 dB six weeks after birth, at eight months practically all mutants were deaf. Endocochlear potential was near zero already in the majority of 6 week-old animals. Abnormalities were observed also in intracellular potentials of the stria vascularis cells which were recorded in vitro and dye-marked. While in marginal cells of CBA mice positive potentials of about 10 mV were recorded, potentials of marginal cells in mutants were near zero. Basal cell potentials were negative in CBA mice (approximately -25 mV) and positive in young mutants (approximately +12 mV). However, in mutants older than 3 months the intracellular potentials of basal cells changed to negativity (approximately -10 mV). The results demonstrate gradual deterioration of hearing function observed in both W/Wv and S1/S1d mutants during first months of the postnatal life. In addition to the dysfunction of stria vascularis, where intermediate cells are missing, also the function of receptors progressively deteriorates.

Action Potentials↗
PubMed1987

DC potentials in different cells of the stria vascularis measured in vitro.

Fine glass microelectrodes were inserted into the stria vascularis (SV) from the endolymphatic side under conditions in vitro. DC potentials were recorded in individual cells of the SV. The electrophoretic dye marking technique was used for identification of cells with different DC potentials. Penetration of the luminal membrane of marginal cells (MC) was accompanied by an unstable transient negative potential of about -15 mV. When the electrode penetrated further into the MC, a positive potential of about +10 mV was recorded. In the basal cells (BC) of the SV a negative DC potential of approx. -45 mV was always measured. Addition of ouabain into the perfusion solution (10(-3) mol/l) abolished the positive potential of MC, whereas the negative potential of BC decreased to approximately one half of the original value. A higher positive potential (+17 mV) was found in the MC of animals which were exposed to noise twenty days before the recording. Results are discussed in the light of the knowledge about localization of different transporting systems within the SV cells.

Animals↗
PubMed1987

Electrophysiological measurements of the stria vascularis potentials in vivo.

Glass microelectrodes were introduced into the stria vascularis (SV) to measure the DC potential profile of the SV in vivo from its apical as well as basal side. The K+ concentration gradient in the lateral cochlear wall was measured by means of double barrel K+-selective microelectrodes. A positive potential 10.4 +/- 6.3 mV higher than the endocochlear potential (EP) was found in the SV. In noise-exposed animals the positive potential found in the SV was 14.6 +/- 7.2 mV higher than the EP. K+ concentration observed during penetration into the SV was in the range of 50-100 mmol/l. Simultaneous measurement of the DC positive potential in the SV and EP showed a nearly parallel time course during anoxia with a tendency to increase the difference between the SV potential and the EP. The difference reached approximately 30 mV 20 min after the beginning of anoxia. It may be assumed that the electrogenic pump localized at the basolateral membrane of the marginal cell (MC) is a source of the positive potential inside the MC and is hence a source of the potential drop across the luminal side of the MC membrane.

Animals↗
PubMed1987

Mechanisms of endocochlear potential generation by stria vascularis.

It is commonly accepted that the endocochlear potential (EP) of the cochlea is generated by an electrogenic transport of potassium into scala media by the marginal cells of stria vascularis. We have studied the potential and potassium concentration gradients as stria vascularis was penetrated with double-barreled potassium selective electrodes in the guinea pig cochlea. Our data demonstrate that a region exists in stria which is positively polarized (higher than the EP), but which has a low (perilymph-like) potassium composition. It is concluded that EP cannot be generated by the marginal cells alone but may involve passive potassium movement across the apical membranes of the basal cells. A model is presented which is consistent with many anatomical and physiological features of stria vascularis.

Animals↗
PubMed1985

The effect of loop diuretics upon summating potentials in the guinea pig.

Ototoxic diuretics, ethacrynic acid (50 mg/kg) and furosemide (80 mg/kg) were injected intravenously in guinea pigs. Cochlear microphonics (CM), summating potentials (SPs) and endocochlear potential (EP) were recorded with a microelectrode in scala media of the second turn. CM changes after the injection were comparable with changes in the EP: an initial decrease was followed by an increase which was significantly slower in the case of the ethacrynic acid. SP changes following either diuretic were different from the CM and EP changes. In the first phase, roughly corresponding with the EP decrease to negative values, all SPs irrespective of the original polarity, attained high positive values. The high positive SPs then decreased and 12-18 min after injection reversed polarity. In the late phase all sounds evoked high negative SPs. Approximately 90 min after injection of furosemide normal SPs were again recorded. The return of SPs to control values was very slow after ethacrynic acid; even 140 min after injection the SPs were abnormal. The observed changes in the SPs were compared with those found during asphyxia and anoxia and are considered to result from diuretic effects on the inner and outer hair cells.

Animals↗
PubMed1981

Longitudinal distribution of cochlear potentials and the K+ concentration in the endolymph after acoustic trauma.

Guinea pigs were exposed to 142 dB third-octave band of noise control at 1 kHz for 1 h. At different times after exposure the endocochlear potential (EP), the anoxic negative endocochlear potential (-EP), the concentration of K+ (K+e) and microphonic potentials were recorded in scala media in four cochlear turns. The remaining hair cells were counted in each animal. Immediately after the exposure, the EP and K+e decreased evenly in all four cochlear turns and gradually returned to normal physiological values in 5-20 days. When measured 20 days after the exposure, essentially normal EP and K+e values were observed, with an apicalwards decline, which was similar to that found along the cochlea in nonexposed animals. Abnormal increased EP was observed in some animals 20 days after the exposure in the first and second turns. In contrast to positive EP and K+e values, the anoxic negative EP attained less negative values in the second turn of exposed animals, i.e., in the turn where the narrow band noise exerted the major destructive effect. An almost normal distribution of hair cells and most negative EP values were found in the fourth turn. The distribution of persistent hair cells correlated positively with the values of the anoxic negative EP and amplitudes of the microphonic potentials. It is assumed that, in addition to the difference in K+ concentration between endolymph and perilymph, the anoxic negative EP is dependent upon the functional state of the organ of Corti.

Animals↗
PubMed1980

Recovery of the endocochlear potential and the K+ concentrations in the cochlear fluids after acoustic trauma.

Intense noise stimulation (142 dB, 1/3-octave-band noise centred at 1 kHz for 1 h) causes damage mainly in the second turn of the cochlea. Several hours (3-5) after the noise exposure, the endocochlear potential (EP) was found to be very low (5.7 +/- 6.0 mV). Similarly, the K+ concentration in the endolymph (Ke+) had decreased to low values (18.9 +/- 9.5 mM). The return of EP and Ke+ to normal values took 5-20 days. In contrast to the Ke+ changes, the perilymph K+ concentration (Kp+) increased slightly after the noise exposure to 4.5 +/- 1.7 mM and returned to normal values one day after the exposure. Differences were found in the time course of the EP, Ke+ and Kp+ changes after the arrest of ventilat ion when animals with acoustic trauma were com,ared with normal healthy individuals. The anoxic EP in noise-exposed animals never decreased to values more negative than -20 mV. The results imply that the inner ear mechanisms maintaining positive EP, Ke+ and Kp+ are severely damaged after acoustic trauma and that their function is restored in 5-20 days. With respect to some parameters (decrease of the EP during anoxia, the value of anoxic negative EP, EP overshoot after reventilation) the inner ear mechanisms are, however, still abnormal.

Acoustic Stimulation↗