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Biomedical subjects

I Antal

Publications and source records attributed to I Antal.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of the degenerative changes in weight-bearing joints following cementing or grafting techniques in giant cell tumour patients: medium-term results.

The aim of this retrospective study was to compare and assess the effect of bone grafting and cementing techniques--two common applications used in the treatment of subchondral giant cell tumours of bone (GCTs)--on the development of degenerative changes in the weight-bearing joints of the lower extremity. Eighty patients were included in this follow-up study, 44 of whom underwent curettage followed by bone grafting, and 36 who had curettage followed by cementation. At the 24-month post-operative examination, significantly less degenerative change was found in patients with bone cement than in those with bone grafting. At the 50-month and later (range: 50-148 months) post-operative examination, however, no significant differences were found between the two groups, indicating that there was a significant acceleration of degenerative changes in the cemented group after the 24-month follow-up.

Adolescent↗
PubMed2006

Application of sucrose fatty acid esters in transdermal therapeutic systems.

Transdermal therapeutic systems (TTSs) were studied applying different sucrose fatty acid esters (SEs) as drug delivery agents. Matrix and membrane controlled TTSs were prepared and compared. Membrane was made from a methacrylic polymer (Eudragit NE) of pH independent permeability which can achieve diffusion controlled drug liberation. Model drug was a water soluble beta-blocker, metoprolol, which has short biological half-life, so applying it in a TTS, the duration of its action could be prolonged. Sucrose fatty acid esters of different fatty acid chain lengths and consequently different hydrophilic-lipophilic balance (HLB) values were studied considering their effect on the metoprolol release from TTSs. Different mathematical models were applied for the evaluation of the release process. The results of the in vitro studies indicated that SEs of shorter fatty acid chain length and higher HLB value increased the amount of released drug about 10 times. SEs could be promising agents in transdermal therapeutic systems to control the drug release and cutaneous absorption.

Administration, Cutaneous↗
PubMed2006

Quantitative estimation of film forming polymer-plasticizer interactions by the Lorentz-Lorenz Law.

Molar refraction as well as refractive index has many uses. Beyond confirming the identity and purity of a compound, determination of molecular structure and molecular weight, molar refraction is also used in other estimation schemes, such as in critical properties, surface tension, solubility parameter, molecular polarizability, dipole moment, etc. In the present study molar refraction values of polymer dispersions were determined for the quantitative estimation of film forming polymer-plasticizer interactions. Information can be obtained concerning the extent of interaction between the polymer and the plasticizer from the calculation of molar refraction values of film forming polymer dispersions containing plasticizer.

Chemistry, Pharmaceutical↗
PubMed2005

Functional outcome and life quality after endoprosthetic reconstruction following malignant tumours around the knee.

Between 1993 and 2002, we treated 43 patients with malignant musculoskeletal tumours of the knee region. All patients had partial resection of the femur or tibia together with endoprosthetic replacement. We were able to follow-up 23 patients with an average follow-up of 30 (12-97) months. Complications occurred in ten cases, of which one was a case of local recurrence. Most of the patients were completely satisfied with their condition, with a decreased walking distance as the only notable restriction. There was no correlation between the functional outcome and life quality assessment and the type of the implanted prosthesis, length of resected bone and type of resection. However, patients with tumours in the distal femur had significantly better functional and life quality outcome than those with a proximal tibial tumour.

Adult↗
PubMed2003

Surgical treatment and prognostic factors in giant-cell tumor of bone.

The rate of local recurrence in the giant-cell tumor of bone (GCT) is influenced by many factors. GCT aggressiveness is related to mitotic activity, aneuploidy of tumor cells, chromosomal abnormality, excessive metalloproteinase expression and alterations in different oncogenes. Statistically, there was no correlation between the recurrence rate and the size and site of tumor, stage of disease and involvement of subchondral bone. However, statistical analysis revealed that the use of adjuvants (phenol, bone cement, etc) and the type of surgical intervention (en block resection versus curettage and grafting) were factors with a prognostic value. Although recurrence or malignant transformation in GCT cannot be predicted yet, about 96% of the patients can be cured. In the majority of cases, recurrences have no fatal consequences for the patient but may lead to various degrees of disability due to repeated and more radical surgical procedures. Joint-sparing surgery and careful curettage with the use of adjuvants should be the treatment of choice whenever possible. In the future, modern instruments of molecular biology will be used to aid the evaluation of primary and recurrent tumors and will have an increasing influence on surgical planning.

Bone Neoplasms↗
PubMed2001

[Biopharmaceutical considerations of dissolution testing used as a prognostic tool for oral drug adsorption].

Drug dissolution is a prerequisite to drug absorption and in vivo effectiveness for almost all drugs given in oral solid dosage forms. Drug absorption depends on the dissolution and solubilization of the drug under physiological conditions, and the permeability across the gastrointestinal tract. Because of the critical nature of the first steps, in vitro dissolution may be relevant to the prediction of biological response. Dissolution tests are applied to choose between formulation factors, assess the lot-to-lot quality of a drug product according to the biobatch; and ensure continuing product quality and performance after certain changes (e.g. in the formulation and manufacturing process, site of manufacture, scale-up). The recently developed Biopharmaceutical Classification System (BCS) has several benefits for recognizing how dissolution tests can be designed and which physiological factors have to be taken into consideration for the in vitro evaluation of solid dosage forms. Choice of test conditions (composition, volume and hydrodynamics of dissolution medium) should be based on where the drug is best absorbed in the gastrointestinal tract, and on whether it is administered in fasted or fed state. Duration of test and physiologically representative media can be selected to simulate gastric and intestinal environments according to the permeability profile of the drug, but mimicking in vivo hydrodynamics remains problematic and further research is required. To provide a basis for predicting the likelihood of achieving a successful in vivo-in vitro correlation, this review summarizes the biopharmaceutical considerations of in vivo drug release in accordance with the BCS.

Administration, Oral↗
PubMed2000

[Results of limb-saving surgery and prognostic factors in patients with osteosarcoma].

Ninety six patients with high-grade osteosarcoma of the extremities were treated between 1986 and 1997 in the authors institution. They were divided into three groups: in group I, all of 75 patients with non-metastatic OS received intensive chemotherapy and underwent surgery. In group II, 9 patients already had metastases at the time of referral. In group III, 12 patients received chemotherapy in delayed or suboptimal form. In group I, local recurrences occurred in 7 per cent (3 patients), metastases in 20 per cent of the patients with limb-saving, whereas these numbers were 3 per cent and 38 per cent in the amputation group. The 5-year disease free survival (DFS) was 72% v 69% in the limb-saving and amputation group, respectively. In groups II and III, 5-year DFS was extremely poor, 10 and 20% only. With univariate analysis, factors having a positive influence on the survival were: tumor volume < 60 cm3, wide or radical surgical margin, distal location of osteosarcoma, cartilagineous ground substance less than 20% and response to chemotherapy. The last 4 variables maintained their significance in the multivariate Cox model as well. Age > 30 showed indirect negative influence on the final outcome (enhanced intolerability to the drugs and less co-operability of the patients etc.). This data confirm the competence of the limb-saving surgery at certain indications beside the amputation.

Adolescent↗
PubMed2000

[Malignant transformation of giant cell tumor in the distal radius. Value of the DNA cytophotometry].

The GCT is a primary bone tumor of intermedia dignity, whereby the forecast of the biological behaviour and outcome is impossible on the base of the conventional histological diagnosis. The authors observed in one of their GCT-patients a malignant transformation of the formerly benign tumor. Through announcement of their case the authors want to call the attention to the importance of the DNA-Cytophotometry and to their possible future additional role in the diagnostics of the GCT and in the prediction of their biological behaviour.

Adult↗
PubMed2000

Mid-foot reconstruction following involvement of five bones by giant cell tumor.

We report on a patient who had giant cell tumor involving multiple bones of the mid-foot. The tumor originated from the navicular bone, but also destroyed the cuboid, and all cuneiform bones. This unusual presentation of giant cell tumor presented a therapeutic challenge for the surgeons. The patient was treated with en bloc resection and the bony defect replaced with a massive iliac crest graft which united within 9 months and has remained stable for 7 years without local recurrence, and with excellent function of the foot.

Adolescent↗
PubMed2000

Development of spherical crystals of acetylsalicylic acid for direct tablet-making.

The production of spherical crystals has recently gained great attention due to the fact that the crystal habit (form, surface, size, etc.) can be modified during the crystallization process. Spherical crystals of ASA were developed by non-typical and typical spherical crystallization techniques. The non-typical spherical crystallization process (conventional stirred tank method) resulted in few monocrystals and non-spherical crystal agglomerates. The typical spherical crystallization process was carried out by the three solvent-system (ethanol-water-carbon tetrachloride). The products were qualified by morphological study, NIR investigation, salicylic acid content, dissolution rate, studies on flowability, compactibility, cohesivity and tablettability. The results demonstrate that only typical spherical crystallization can be recommended for the production of spherical crystals of ASA. Only product made by this technique shows excellent flow properties and favourable compactibility, cohesiveness and tablettability values.

Aspirin↗
PubMed1999

[Dual fluorescence in situ hybridization analysis of synovial sarcoma].

Synovial sarcoma have (about in 95% of the cases) the specific and characteristic reciprocal chromosomal translocation t(X; 18) (p11.2; q 11.2). Application of dual-colour fluorescence in situ hybridization (FISH) on interphase nuclei to identify the specific translocation has a diagnostic importance for daily pathological practice. For visualisation of the translocated chromosomal fragments of synovial sarcoma cells on imprint smears, chromosome X painting probes and chromosome 18 centromeric probes were used. Our present study indicates that the precise preoperative diagnosis of synovial sarcoma using dual-colour FISH is possible on smears and this possibility (to identify specific chromosomal translocations in soft tissue tumours) is a landmark in the preoperative diagnosis of soft tissue sarcomas.

Adult↗
PubMed1999

The prognostic significance of DNA cytophotometry and proliferation index (Ki-67) in giant cell tumors of bone.

We studied DNA ploidy by smear cytophotometry and proliferation activity by Ki-67 MIB immunohistochemistry in 69 primary and recurrent giant cell tumors (GCT) from 50 randomly selected patients. The obtained results were evaluated with comparisons made to the available clinical data. From the 46 primary tumors 63% showed diploidy and 37% aneuploidy. A significantly (P=0.026) higher recurrence rate (64%) was observed in aneuploid than in diploid tumors (31%). In the course of the recurrences, both the ratio of aneuploid tumors as well as the proliferation index of the tumors increased, though the degree of the latter was non-significant. Aneuploidy did not mean an unambiguous tendency towards malignant transformation; however, a close follow-up of recurrent aneuploid tumors, and wide excision of the recurrence instead of intralesional curettage are the recommended procedures. The DNA cytophotometry and proliferation index of GCTs--as compared to other histologic examinations--are of prognostic value in the evaluation of the recurrence potential of the GCTs.

Adolescent↗
PubMed1999

[Modification of drug release with application of pharmaceutical technological methods].

Pharmaceutical technological methods, which enable the development of controlled release, prolonged action solid oral dosage forms, are of great importance. The purpose of our study was to apply these methods and evaluate the prepared samples. The first type of the samples were individually coated separated particles, prepared by mixing with lubricant to built up a lubricant film layer on the surface of the drug crystals. The next group of the samples were separately coated particles--wall material was wax--prepared using the following two technologies: fluidisation atomisation process and hot-melt coating. The third group of the samples was the matrix type, where the core material was mixed into the molten mass of the thermosoftening natural coating material or into some synthetic polymer film material. In some cases several surface active agents were added to the molten mixture to achieve a modification in the drug release process and the examined parameters of the samples. For the comparative evaluation of the prepared dosage forms drug release determination and kinetical analysis of the process were maintainly used. The surface morphology was examined on the base of scanning electronmicroscopic and optical microscopic studies. Among the physical and physico-chemical studies particle size analysis was carried out and dynamic contact angles of the solid samples as well as the surface tension decreasing effect was measured to determine the modifying properties of surface active excipients. To sum up, our results demonstrate that the economical and environmentally acceptable melt coating technology was justified as applicable advantageously in a large number of cases for the development of controlled release devices of highly watersoluble drug, even the medical substance is an organic compound having adjustable thermostability.

Delayed-Action Preparations↗
PubMed1998

Fibrous dysplasia associated with intramuscular myxoma (Mazabraud's syndrome): a long-term follow-up of three cases.

The association between of fibrous dysplasia and intramuscular myxomas is extremely rare. The authors summarize the characteristics of Mazabraud's syndrome, as well as its clinical course on the basis of 24 cases reported in the literature and 3 cases of their own. The syndrome is quite uniform, and mostly occurs in women. Usually the presentation of poliostotic fibrous dysplasia bilaterally in the lower limbs and pelvic bones is followed by the appearance of multifocal intramuscular myxomas in the adjacent muscles, mostly decades later. These hamartomas tend to recur locally or symmetrically in the ipsilateral muscle groups and may reach enormous size without treatment. Malignant transformation (osteosarcoma, fibrosarcoma) on the basis of fibrous dysplasia in Mazabraud's syndrome has been reported in the literature. In our cases, however, in spite of the many recurrences, and the enormous size of the tumours, no malignant transformation was noted in either the fibrous dysplasias or the intramuscular myxomas during the long follow-up time (31 years for fibrous dysplasia and 16 years for myxomas). Early wide surgical excision and a careful long-term follow-up for the often very late recurrences of the myxomas is suggested in Mazabraud's syndrome.

Adolescent↗