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Biomedical subjects

M Matejka

Publications and source records attributed to M Matejka.

At least 37 records · Page 2Linked to original sources
PubMed1990

Local benefit of prostaglandin E2 in radiochemotherapy-induced oral mucositis.

In 15 patients suffering from maxillofacial cancer with radiochemotherapy-induced oral mucositis the local application of prostaglandin E2 (PGE2) tablets, 0.5 mg four times a day at a 4-h interval was performed. Plasma determination of the bicyclo-prostaglandin E2 metabolite showed no significant amount of the locally applied substance in the circulation. It is claimed that for this particular indication, PGE2 is a potent locally acting compound without affecting circulating levels.

Aged↗
PubMed1989

Enhancement of human dental cyst PGI2 formation by platelet derived growth factor and its role in cyst growth and bone resorption.

Various prostaglandins, particularly PGE2 and PGI2, appear to play a major role in osteolytic processes. Radiochromatographic studies have demonstrated that 6-oxo-PGF1-alpha is a major product of exogenously added arachidonic acid in human dental cysts. As platelets may also act as inflammatory cells, platelet-derived growth factor might also have a PGI2-stimulating influence in such cysts. Eleven human dental cysts were examined by a radioimmunoassay and bioassay which can show PGI2 synthesis in human dental cysts without addition of PDGF. Incremental PDGF addition caused a highly significant increase in the rate of PGI2 synthesis. PGDF thus stimulates PGI2 synthesis in chronic inflammatory processes in vitro and may thereby elicit or accelerate osteolysis.

6-Ketoprostaglandin F1 alpha↗
PubMed1989

The optimal processing of plasma samples for the determination of bicyclo-PGE in patients with malignant maxillofacial tumors.

Prostaglandins (PGs) have been shown to be increased in several tumor tissues. PGE2 and PGF1-alpha Radioimmunoassays (RIAs) have been widely used for quantitative PG-measurements in cancer patients. Our results indicate that optimal processing of plasma samples for the determination of bicyclo-PGE2 is of the highest importance in order to get reproducible results. Therefore it is necessary to fulfill the following requirements: 1. 30 minutes rest before sampling; 2. Avoid venous occlusion; 3. Use constant needle diameter; 4. Precooled anticoagulant; 5. Addition of a cyclooxygenase inhibitor is necessary; 6. Control of processing temperature; 7. Storage at -70 degrees C less than -20 degrees C; 8. Control of storage time; 9. The samples have to be examined after thawing once; 10. Only blood samples processed under the above discovered optimal conditions are of clinical relevance; 11. An international standardization for the processing of plasma samples seems to be necessary considering all these requirements; 12. In 41 patients with maxillo-facial carcinomas the PG-value was significantly higher than in the controls; 13. A RIA-evaluation methodologically properly done may be used as an additional aid for clinical monitoring of the patients.

Adult↗
PubMed1989

[Conditions of the gingiva around endosteal implants with attached and unattached mucosa].

The condition of the peri-implant mucosa is critical for the long-term success of endosteal implants. 111 endosteal implants (IMC and Brånemark) were examined to see whether peri-implant gingival attachment to bone and peri-implant inflammatory reactions correlated with implant stability. A direct relation was found exist between peri-implant mucosal attachment and pocket depth around implants, while the severity of peri-implant inflammatory reactions did not correlate with implant stability. But this might be explained by the relatively short implant residence of 5 years at the time of the follow-up study.

Biocompatible Materials↗
PubMed1989

[Bone resorption at the entry of osseointegrated implants--a biomechanical phenomenon. Finite element study].

Using finite element analysis, osseointegrated implants exposed to physiologic stresses were examined for the occurrence of stress concentrations at the site of implant entry into bone and factors affecting such stress concentrations were looked for. Qualitative and quantitative alterations of stresses around endosseous implants were computed for different implant sizes, implant materials and cortical thicknesses. The following factors were found to be important for reducing peak stresses in cortical bone: Cylindrical implants are preferable to conical implant shapes. Large implant diameters provide for more favorable stress distributions. Implant materials should have a modulus of elasticity of at least 110,000 N/mm2. Slipping between implants and cortical bone is desirable.

Bone Resorption↗
PubMed1989

[Ionomeric vitreous cement for retrograde root filling].

In an in vitro study the sealing properties of materials commonly used for retrograde filling of apicectomized teeth were investigated in extracted teeth and compared with those of ionomeric vitreous cement. Materials tested included: --Heat-sealed guttapercha; --Guttapercha + phosphate cement; --Amalgam; --Standardized ceramic pins (Ulm system); and --Ionomeric vitreous cement. Sealing was established by methylene blue perfusion. Seals produced by heat-sealed guttapercha, guttapercha + phosphate cement and non-gamma-2 amalgam were found to be inferior to those obtained with ionomeric vitreous cement and standardized aluminium oxide ceramic pins.

Dental Amalgam↗
PubMed1989

[Anatomy of the atrophic mandible. 1. The location of the mandibular canal in the atrophic mandible].

43 atrophic left hemimandibles were divided by 6 saw cuts made between the mental foramen and the third molar to analyze the location of the mandibular canal. Mandibles were classified by the severity of alveolar absorption using Atwood's classification and changes in the distances of the mandibular canal from the superior and inferior borders of the mandibular body were correlated wit the degree of atrophy. Measurements were obtained with a digitizer and a computer and results were analyzed statistically. The following statistically significant observations were made: The distance of the mandibular canal to the external lingua and buccal cortical layers did not change with increasing atrophy, but remained remarkably constant. By contrast, highly significant changes in the distance of the mandibular body were found to be present. These were more pronounced at the superior than at the inferior border. The changes seen were consistently most severe at the level of the first molar. Prior to surgical interventions involving an atrophic mandible the location of the mandibular canal should invariably be identified by imaging techniques such as orthopantomography, telemetric X-rays, tomographies, CT and MRI, if indicated, in order to avoid injuries of the inferior alveloar nerve and preclude forensic consequences.

Aged↗
PubMed1988

[Collection, preparation and storage of human plasma for radioimmunologic determination of thromboxane B2].

There are at present several methods available for the quantitative determination of thromboxane B2. However, they give results differing in precision and biological information. If it were possible to exclude sampling and storage artefacts, radioimmunological plasma thromboxane B2 measurement would be the method of choice for routine clinical determinations. The optimum conditions for processing the plasma for such purposes were assessed in 10 healthy volunteers (6m, 4f, 24-37a). They include a 30-minute resting period before blood sampling, constant needle diameter, blood withdrawal without venous occlusion, proper anticoagulation and cyclooxygenase inhibition. Storage at -70 degrees C for less than 2 weeks and the avoidance of repeated freezing and thawing are further prerequisites. In contrast to widely-held opinion, the plasma levels of thromboxane B2 obtained using these precautions are of practical value, roughly comparable to those employing the platelet proteins beta-thromboglobulin and platelet factor 4. However, practically speaking determinations are limited to a small number of carefully handled samples. Hence, the method cannot be unreservedly applied to daily routine clinical use.

Blood Platelets↗
PubMed1988

Indium 111-A-bleomycin--a new tracer for imaging orofacial neoplasms.

Forty-six patients with maxillofacial squamous cell cancer of variable keratinization underwent radioisotope diagnosis using Indium 111-A-bleomycin. This new technique was applied to expand the battery of diagnostic tools available for detecting maxillofacial neoplasms. Its high specificity (100%) and sensitivity (96%) make it well suited for detection of both local and distant recurrences as well as tumor regrowth. Preliminary whole body retention measurements also indicate that this technique looks promising for potential therapeutic use.

Aged↗
PubMed1988

Local prostaglandin E2 in patients with oral malignancies undergoing chemo- and radiotherapy.

Patients undergoing chemo- and/or radiotherapy for malignancies were often found to develop annoying inflammation of the oral mucosa. As prostaglandins are known to be cytoprotective. Prostaglandin E2 was given to 10 patients who received combined radio- and chemotherapy for oral neoplasms. Patients receiving PGE2 reported substantially less intense pain then those in the control group. Our statistically significant results indicate that topical treatment of side effects produced by combined radio- and chemotherapy of oral neoplasms with PGE2 holds promise and is clearly superior to conventional treatment modalities.

Adult↗