Biomedical subjects

A Radek

Publications and source records attributed to A Radek.

At least 19 recordsLinked to original sources

PubMed2005

The effect of selective sst1, sst2, sst5 somatostatin receptors agonists, a somatostatin/dopamine (SST/DA) chimera and bromocriptine on the "clinically non-functioning" pituitary adenomas in vitro.

The aim of the work was to investigate the effects of somatostatin analogs acting selectively on sst1 (BIM-23926), sst2 (BIM-23120) and sst5 (BIM-23206) receptor subtypes on the viability of "clinically non-functioning" pituitary adenomas in vitro. The effects of native SST (SST-14), a SST/DA chimera (BIM-23A387) and a D(2)-dopamine receptor agonist bromocriptine (BC) were also examined. The study was performed on 10 surgically removed pituitary macroadenomas, diagnosed before surgery as "non-functioning". A part of each tumor was mechanically dispersed and digested with collagenase to isolate the tumoral cells. Another part of each tumor was fixed, embedded in paraffin and immunostained to reveal the pituitary hormones and SST receptor subtypes (sst1, sst2A, sst2B, sst3, sst4, sst5). The tumoral cell suspensions were incubated for 24 h with the substances mentioned above. The quantity of viable cells was estimated using the EZ4U system. The results were compared with the immunohistochemical evaluation of the hormonal profile of adenoma and the sst receptor subtype immunoreactivities present. The findings indicate that selective sst1, sst2 and sst5 receptors agonists, SST/DA chimera and D(2)-dopamine receptor agonist bromocriptine affect the viability of some, but not all, "clinically non-functioning" pituitary adenomas in vitro. The most effective was bromocriptine. The investigated somatostatin analogs including SST/DA chimera exerted roughly similar inhibitory effects. Further studies are needed to fully evaluate the potential usefulness of these compounds in the pharmacological treatment of "non-functioning" pituitary tumors.

Adenoma↗

PubMed2001

Immediate stiffness of the C5-C6 segment after discectomy with the Cloward technique: an in vitro biomechanical study on a human cadaveric model.

OBJECTIVE: To determine whether the Cloward technique of cervical discectomy and fusion increases immediate postoperative stiffness of single cervical motion segment after application of interbody dowel bone graft. METHODS: We measured and compared the stiffness of single-motion segments in cadaveric cervical spines before and immediately after interbody fusion with the Cloward technique. Changes in range of motion and stiffness of the C5-C6 segment were measured in a bending flexibility test (flexion, extension, lateral bending and axial rotation) before and after a Cloward procedure in 11 fresh-frozen human cadaveric specimens from the 4th through the 7th vertebrae. RESULTS: The Cloward procedure produced a statistically significant increase in stiffness of the operated segment in flexion and lateral bending when compared with the intact spine. The less stiff the segment before the operation, the greater the increase in its postoperative flexural stiffness (statistically significant). The Cloward procedure produced nonuniform changes in rotational and extensional stiffness that increased in some specimens and decreased in others. CONCLUSION: Our data demonstrate that Cloward interbody fusion increases immediate postoperative stiffness of an operated segment only in flexion and lateral bending in cadaveric specimens in an in vitro environment. Thus, Cloward fusion seems a relatively ineffective method for increasing the stiffness of a construct. This may add to discussion on the use of spinal instrumentation and postoperative management of patients after cervical discectomy, which varies from bracing in hard collars through immobilization in soft collars to no external orthosis.

Adult↗

PubMed2001

[Stereotactic biopsy and brachytherapy in the diagnostics and treatment of brain tumors--preliminary report].

Promising results have been obtained using brachytherapy in the treatment of brain tumors. Between November 99 and August 2000, 28 patients with brain tumors (15 newly diagnosed gliomas, 11 recurrent gliomas, 2 metastases) underwent implantation of temporary iridium 192 sources with stereotactic technique. This group received external beam radiation therapy (45 Gy) following implantation. Patients were followed-up with CT scans every 3 months. Serious complications occurred in two patients (postradiation brain oedema). Median survival has not been assessed due to short follow-up period and small number of patients. Further clinical assessment is required especially long-term follow-up. Brachytherapy appears to be a useful technique for the treatment of selected brain tumors.

Adult↗

PubMed2000

Mechanical properties of the human brachial plexus.

This study shows measurements of force and elongation during experimental traction of human brachial plexus. Experiments were realised on fresh cadaveric specimens, mechanism of traction injury of brachial plexus was simulated. Predominant lesion provoked by direct lateral traction of isolated brachial plexus was avulsion of the roots. Epineural mechanical failure as first lesion occurred at anterior margin of avulsed roots in the proximity of intervertebral foramen. The force leading to rupture of brachial plexus ranged between 217.7N-546.3N, stress value between 1.3 N/mm2-3.5 N/mm2. Elongation until rupture was 19.6%-58.8% of initial length.

Biomechanical Phenomena↗

PubMed2000

Conception of the cervico-brachial protector for motorcycle drivers.

The increasing popularity of motorcycles increases the role of motorcycle accidents as a main cause of brachial plexus injuries. In view of the high social cost of treatment of the victims it seemed desirable to devise some kind of protective clothing for motorcyclists. The protective clothing devised by teams from Department of Neurosurgery, TRICOTEXTIL--and Aeronautics and Applied Mechanics Institute, consists of the following parts: cervical collar--acting against force causing lateral bending and extension of cervical spine, shock-absorptive shoulder pads--acting against the impact energy partially absorbing it and partially transmitting to the dorsal stiff bar, dorsal stiff bar and sacroiliac belt--partially immobilizes the thoracic and lumbar spine, acts against its compression, transmits the impact energy to the iliac crests and hips. The expected biomechanical effects of the cervico-brachial protector are as follows: In brachial region it should diminish the impact energy by its partial absorption and partial transmission along dorsal stiff bar to sacroiliac belt. It should act against excessive cervical spine motion--mainly against lateral bending and extension. It should act against excessive depression of the shoulder. The protective system built in the jacket should co-operate with the helmet of motorcycle driver. It should be comfortable for the driver and conform to security standards. Prototype of the protector underwent kinetic sledge tests in Industrial Motorization Institute (PIMOT), Warsaw, with the use of Hybrid Dummy II.

Accidents, Traffic↗

PubMed1999

Anterior transsternal approach to the upper thoracic spine.

Cervicothoracic junction and upper thoracic spine down to T4 can be reached through anterior approach via sternotomy. Transsternal approach is the best route to gain access to lesions localized within vertebral bodies of the upper thoracic spine allowing for their resection, interbody fusion and replacement with bone cement. Consecutive modifications of transsternal approach evolved towards less extensive osteotomy from full median sternotomy, through manubriotomy with clavicle resection to partial lateral manubriotomy. Less extensive modifications provide limited lateral exposure of the spine and are more demanding technically. We present two cases of the upper thoracic spine tumours operated on through full medial sternotomy. We believe that median sternotomy has several advantages over less extensive modifications: it is technically simple to perform approach for trained thoracic surgeon, safer as it provides better exposure of the mediastinum and thus sufficient control of great vessels including subclavian ones, gives better exposure of T3, T4 and even T5 vertebral bodies, allows perpendicular sight and attack to anterior surface of the upper thoracic spine and therefore good visualizing of the posterior longitudinal ligament and dura, do not destabilize shoulder girdle nor affect function of the upper limb. Additional caudal exposure of the thoracic spine as down as T5 can be obtained by dissecting a plane between the brachiocephalic vein, vena cava superior and ascending aorta.

Aged↗

PubMed1989

Inhibitory effect of calcium channel blockers on proliferation of human glioma cells in vitro.

The effects of 2 specific calcium channel blockers, verapamil and nimodipine, on the proliferation of human glioma tumour cells were investigated in vitro. Tumour tissues for primary cell cultures were obtained bioptically from 3 patients with the histopathological diagnosis of glioblastoma. The [3H]-thymidine incorporation into glioma tumour cells DNA was used as a sensitive index of the cell proliferation. It was found that verapamil (10(-4)-10(-5) M) and nimodipine (10(-4)-10(-6) M) significantly inhibited the [3H]-thymidine uptake in a dose-related manner. The inhibitory effect of both calcium channel antagonists was reversed by simultaneous addition of calcium chloride (5 x 10(-3) M). These results indicate that verapamil and nimodipine may exert an antiproliferative effect on glioma cells growth acting through a blockade of specific voltage-dependent calcium channels.

Calcium↗

PubMed1989

Cysto-atrial shunt treatment of intracranial arachnoid cysts.

Four cases of intracranial arachnoid cysts treated with cysto-atrial shunt are reported. Clinical findings, radiological evaluation and operative results are reviewed. An important role of CT diagnosis for revealing of this kind of lesion is stressed by authors. Two patients aged from 21 to 27 years had supratentorial cysts. A 12 year old boy and a man aged 26 years had cysts in the posterior fossa. All patients were treated by computerized tomography. All of them were diagnosed with cysto-atrial shunt and a standard low-pressure Cordis-Hakim valve was inserted into the cyst. Clinical improvement was observed in every patient. A follow up CT revealed that a cyst collapsed in one case. Cysto-atrial shunt procedure is recommended as a favourable and a simple method of surgical treatment of intracranial arachnoid cysts.

Adult↗

PubMed1989

Experimental evaluation of the net "Dallop" covered with collagen as the dural substitute.

Evaluation of the usefulness of the net "Dallop" produced by Tricomed Lódź covered with collagen to the dural defects reparation was analysed. This new original product of Lódź Technical University was compared with widely used in neurosurgery "Zenoderm" produced by Ethicon and "Duratexol" produced by Czechoslovakia. The trial was conducted on 38 rabbits: 4 as a control group (just an original dura sutured after incision with Mersilk Ethicon sutures), 19 with implanted the net "Dallop" covered with collagen, 11 with the "Zenoderm" and 4 with the "Duratexol". Animals were sacrificed after 3, 14, 30 or 90 days after surgery. There were no significant differences between all analysed groups in clinical, macroscopical and morphological investigations. No negative local reactions in histopathological evaluation of the net "Dallop" covered with collagen were observed. The results of our investigations show that the net "Dallop" covered with collagen seems to be the "Zenoderm" and the "Duratexol" dural substitute.

Animals↗

PubMed1988

Inhibition of cell proliferation of human gliomas by benzodiazepines in vitro.

The effects of several benzodiazepines (diazepam, clonazepam, Ro 15-1788 and Ro 5-4864) on cell proliferation of 2 human gliomas were estimated in vitro by means of [3H]-thymidine uptake assay. It was found that all tested benzodiazepines suppressed [3H]-thymidine incorporation into the DNA of glioma cells, the effects being stronger in case of peripheral-type benzodiazepine receptor ligands. The results indicated that benzodiazepines might exert an antiproliferative action on glioma tumour cells growth.

Astrocytoma↗

PubMed1987

Somatostatin suppression of meningioma cell proliferation in vitro.

Considering the presence of a stereospecific receptor for somatostatin (SST) in human meningioma cells and the possible involvement of this neuropeptide in the growth control of certain meningioma cell lines, the effects of SST on the proliferation of human meningioma cells in vitro was investigated. Tumour tissues for primary cell cultures were obtained surgically from 2 women with histopathological diagnosis of meningothelial meningioma. The incorporation of [3H]-thymidine into meningioma cells DNA was measured as an index of the cells proliferation. It was shown that SST (10(-7)-10(-5) M) significantly inhibited the [3H]-thymidine incorporation. The results have indicated that SST may have an antiproliferative effects on the meningioma tumour cells in vitro.

Adult↗

PubMed1986

Perineurial differentiation in interchange grafts of rat peripheral nerve and spinal root.

The differentiation of the perineurium has been examined in replacement nerve grafts in which segments of the third lumbar dorsal root and the peroneal division of the sciatic nerve of rats were excised and resutured into the gaps. This was compared with perineurial differentiation in interchange grafts in which segments of peroneal nerve were grafted into the third lumbar dorsal root and vice versa. It was concluded that not only the origin of the graft but also the local tissue environment is important in determining the morphological outcome, the latter having the predominant influence.

Animals↗

PubMed1983