Biomedical subjects

Z Németh

Publications and source records attributed to Z Németh.

At least 19 recordsLinked to original sources

PubMed2000

The effect of liquid crystalline structure on chlorhexidine diacetate release.

The aim of this study was to examine different liquid crystalline preparations containing chlorhexidine diacetate and to find connection between their structure and the kinetic of drug release. Nonionic surfactant, Synperonic A7 (PEG(7)-C(13-15)) was selected for the preparation of the examined liquid crystalline systems. Mixtures of different ratios of Synperonic A7 and water were produced. By increasing the water content of the systems, lamellar and hexagonal liquid crystal structures were observed. For the analysis of the prepared liquid crystalline systems polarising microscopy, rheology study, differential scanning calorimetry and dynamic swelling tests were carried out. The chlorhexidine diacetate release was examined by Franz-type vertical diffusion cell apparatus. The chlorhexidine diacetate release from hexagonal liquid crystalline preparations was characterised by zero-order release kinetics, while the drug release from lamellar liquid crystalline systems was described by anomalous (non-Fickian) transport. The results indicate that the drug release kinetic is strongly dependent on the liquid crystalline structure.

Anti-Infective Agents, Local↗

PubMed2000

Possibilities of preventing osteoradionecrosis during complex therapy of tumors of the oral cavity.

In recent years, there has been a dramatic increase in the number of tumors of the head and neck. Their successful treatment is one of the greatest challenges for physicians dealing with oncotherapy. An organic part of the complex therapy is preoperative or postoperative irradiation. Application of this is accompanied by a lower risk of recurrences, and by a higher proportion of cured patients. Unfortunately, irradiation also has a disadvantage: the development of osteoradionecrosis, a special form of osteomyelitis, in some patients (mainly in those cases where irradiation occurs after bone resection or after partial removal of the periosteum). Once the clinical picture of this irradiation complication has developed, its treatment is very difficult. A significant result or complete freedom from complaints can be attained only rarely. Attention must therefore be focussed primarily on prevention, and the oral surgeon, the oncoradiologist and the patient too can all do much to help prevent the occurrence of osteoradionecrosis. Through coupling of an up-to-date, functional surgical attitude with knowledge relating to modern radiology and radiation physics, the way may be opened to forestall this complication that is so difficult to cure.

Antineoplastic Agents, Alkylating↗

PubMed2000

[Care of patients with oral cavity tumors in the hospital and at home].

This study reports on experience acquired during the care of patients who could not participate in surgery, chemotherapy or radiation therapy because of the extent of the primary, recurrent or metastatic tumour, or because of the deterioration of the general condition or (in the event of recurrence), intervention with a curative aim could not be performed for the mentioned reasons. In these cases, improvement or preservation of the quality of life is the fundamental goal to be achieved at all times, for these patients must receive the best possible supportive treatment for the remainder of their lives, Unfortunately, the quaranteeing of this often tends to become mainly a financial question rather than a professional one. The medical staff has very little chance to influence the financial aspects, and must therefore do everything possible to ensure the highest possible level of care during hospitalization. Attention is drawn to the significant roles to be played by the family, the family doctor, the various home-care services and the hospice.

Analgesics↗

PubMed1999

Intra-arterial preoperative cytostatic treatment versus preoperative irradiation: A prospective, randomized study of lingual and sublingual carcinomas.

BACKGROUND: For several decades, both preoperative intra-arterial chemotherapy and preoperative irradiation have been accepted treatments for patients with tumors of the head and neck. Unfortunately, arguments have often been put forward in favor of one or other of the two methods, but without the performance of an objective, randomized investigation. To resolve this situation, the authors have carried out a multicenter, randomized prospective study of selected patients with a view to deciding which method affords better results in complex tumor therapy from the aspects of survival and postoperative quality of life. METHODS: One hundred thirty-one patients with operable sublingual or lingual squamous cell carcinoma in stages T2NXM0 to T4MXM0 were randomized into 2 groups: 1 group participated in preoperative chemotherapy with cisplatin and epirubicin (total doses: 200 mg cisplatin, 120 mg epirubicin) via the external carotid artery, whereas the other group received preoperative radiation therapy (46 grays). Following subsequent radical surgery, the patients received regular follow-up for 5 years. RESULTS: By the end of the 5 years, 95 of the 131 patients had conformed to the protocol. Of those 95, 47 had received preoperative chemotherapy and 48 preoperative irradiation. After 5 years, 18 of the 47 patients who received chemotherapy and 15 of the 48 patients who received irradiation were still alive and tumor free. A few more patients had died of recurrence or regional metastasis in the chemotherapy group (23 patients) than in the irradiation group (20 patients). Occurrence of a second carcinoma was 3 times as frequent in the irradiation group (9 patients) as in the chemotherapy group (3 patients). Overall, the survival rates were by-and-large the same for the two groups. Regarding postoperative quality of life, the chemotherapy group presented a more favorable picture. CONCLUSIONS: The long term survival results subsequent to preoperative intra-arterial chemotherapy or preoperative radiotherapy were practically the same. Regarding postoperative quality of life, patients who underwent intra-arterial chemotherapy appeared to be in a slightly more favorable situation. The authors consider it important to stress these findings, as they are not aware of a similar randomized study of patients with tumors of the oral cavity.

Adult↗

PubMed1999

[Changes in body fluid compartments estimated by multifrequency bioelectric impedance analysis in patients treated by hemodialysis].

Bioimpedance is a simple non-invasive method of assessing body composition. The aim of this study was to investigate the effect of changes in body fluid related to haemodialysis on measured bioimpedance parameters, to determine correlation between bioimpedance data and the volume of ultrafiltratum, and to collect data on alterations of body fluids resulting from a treatment. Measurements were done on 19 patients (mean age 36.7 years) prior to and after haemodialysis. After dialysis we found significantly higher impedance values on each measured frequency (1, 5, 10, 50, 100 kHz) (p < 0.001). An inverse correlation was found between the changes in body weight (x) and resistance at 50 kHz (y): y = 8.4830-2.1850x (r = 0.7167, p < 0.01). Total body water calculated by bioimpedance analysis (BIA) decreased from 38.47 +/- 8.567 litres (56.07%) to 35.06 +/- 8.045 significantly (p < 0.001), and the reduction of extracellular water proved to be also significant [from 15.76 +/- 2.992 litres (22.97%) to 14.06 +/- 2.736 litres (21.17%), p < 0.001]. The relationship between the change in calculated body water (x) and the volume of ultrafiltratum (y) is: y = -0.5590 + 0.5864x (r = 0.4898 p < 0.05), bioimpedance in our study overestimated the fluid loss by 55%. The intradialytical shifts between extra- and intracellular spaces might be responsible for the difference in the two values.

Body Fluids↗

PubMed1999

Correlation of the combination of alcoholism and smoking with the occurrence of cancer in the oral cavity. A screening study in an endangered population.

A number of studies have previously been carried out on patients with tumors of the oral cavity, a majority of whom proved to be heavy smokers and heavy drinkers. However, we are not aware of literature reports relating to the converse situation: a study of alcoholics and strong smokers to establish the incidence of malignant processes of the oral cavity among them. Accordingly, the present aim was to investigate the occurrence of oral cavity lesions among 300 subjects who were alcoholic and heavy smokers and of the opinion that they had no tumor. Malignant processes were detected in the oral cavity or its environment in 2.66% of the 300 subjects, and more than 19% of them were found to harbour benign tumors and precancerous lesions. These investigations highlight the importance of screening examinations of the endangered population.

Adult↗

PubMed1999

A new advanced surface modification technique--titanium oxide ceramic surface implants: the background and long-term results.

This paper discusses the background of advanced surface modification technologies and presents a new technique that forms a titanium oxide ceramic coating with relatively long-term clinical use. Three general techniques are used to modify surfaces: adding or removing material, or changing material already present. Surface properties can also be changed through laser or electron beam thermal treatment without adding or removing material. The new technique outlined in this paper describes producing a corrosion-resistant, 2000 A to 2500 A thick, coherent crystalline oxide ceramic layer on the surface of titanium implants. The layer is grown electrochemically from the bulk of the metal and modified by heat treatment. Compared with implants covered with other coatings, the improved properties of such oxide ceramic-coated implants include the advantages of higher external hardness and greater adherence between the titanium and the ceramic oxide coating. The virtually perfect insulation between the tissue and the metal prevents metal allergy. The coated implants were subjected to various physical and chemical tests and electron microscopy for a qualitative characterization. Finally, these implants (plates, screws for maxillofacial osteosynthesis, and dental root implants) were followed in surgical practice for 10 years. Tests demonstrated and the acquired experience confirmed the good properties of the titanium oxide ceramic-coated implants.

Ceramics↗

PubMed1998

Foam Control by Silicone Polyethers-Mechanisms of "Cloud Point Antifoaming"

The mechanism of antifoaming in a nonionic Triton X-100 surfactant solution with silicone polyethers (SILWET L-7210, L-7230, and L-7500), the so-called "cloud point antifoams," was investigated. The cloud point (CP) studies showed that the CP of a Triton X-100/silicone polyether mixed system is between the CP of the foaming and the antifoam surfactants, due to mixed micelle formation. It was found that the foam stability drops at a certain temperature-which we called the enhanced foam collapse temperature (EFCT)-which was a few degrees Celsius below the CP of the solutions. Single films were also formed from the same systems, and their stability and drainage were observed. Film thinning accelerated with temperature near the cloud point, but this cannot explain the lower foam stability. It was observed that while at low temperatures black film formed, above the EFCT the film ruptured just before black film formation could have begun; the rupture was probably caused by unstable black spots. It is suggested that at the EFCT (near the CP) the net interaction between the film surfaces becomes attraction due to the same reason that causes the CP: the hydrophilic parts (polyethylene oxide) of the nonionic surfactants lose their hydrate water and thus, the steric repulsion between the surfaces diminishes. The EFCT and the CP are not necessarily the same because the composition of the foam and micelle surfaces, respectively, can be different. The antifoaming action was also tested above the CP of the solution and it was observed that another antifoaming mechanism also acts there: the phase-separated surfactant drops get trapped in the thinning foam films and the trapped drops rupture the films by bridging. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

ATP released by LPS increases nitric oxide production in raw 264.7 macrophage cell line via P2Z/P2X7 receptors.

P2Z/P2X7 receptor is a particular type of purinoceptor, which is selectively expressed on the surface of immune cells in neuronal and non-neuronal tissues. Despite intensive research on its involvement in the immune response, the exact mechanism whereby it affects intercellular signaling is far from clear yet. In this study, the effect of activation P2Z/P2X7 receptor was investigated on the bacterial lipopolysaccharide induced nitric oxide production in RAW 264.7 macrophage call line using the nitrite/nitrate assay. The P2Z/P2X7 receptor agonist 3'-O-(4-benzoylbenzoyl)-adenosine 5'triphosphate increased concentration-dependency the lipoplysaccharide (10 microg/ml) induced nitric oxide production between 10 microM and 250 microM. ATP also increased nitric oxide production in response to lipopolysaccharide, while ADP, 2-methylo-thio-adenosine 5'-triphosphate and adenosine 5'triphosphate-gamma-S was without effect. Pretreatment with oxidized adenosine triphosphate, the selective P2Z/P2X7 receptor antagonise (300 microM-1 microM) strongly decreased lipopolysaccaride induced nitric oxide production. Furthermore, on macrophages, pretreated with oxidized adenosine 5'-triphosphate (300 microM-1 mM), 3'-O-(4-benzoylbenzoyl)-adenosine 5'-triphosphate and ATP did not affect lipopolysaccharide induced nitric oxide production. 15 min lipopolysaccharide treatment induced a transient and reversible release of endogenous ATP from RAW 264.7 cells, measured by the luciferin-luciferase assay. The effect of lipopolysaccharide to promote ATP release was concentration-dependent between 1-10 microg/ml. In summary, our results show that P2Z/P2X7 receptor activation results in an increase in nitric oxide production in response to lipopolysaccharide challenge. Since the P2Z/P2X7 receptor antagonist oxidized adenosine triphosphate decreased lipopolysaccharide induced nitric oxide production, and lipopolysaccharide was able to promote ATP release from macrophage cells, it seems likely that endogenous ATP is involved in nitric oxide formation during endotoxin challenge.

Adenosine Triphosphate↗

PubMed1998

Plant tissue culture as a model for study of diversity in formaldehyde binding.

The effect of endogenous formaldehyde (HCHO) deprivation with dimedone - as abiotic stress - was investigated on the methylation-demethylation reactions in Datura innoxia Mill. callus cultures. The matrix assisted laser desorption/ionization mass spectrometric (MALDI MS) investigation of the culture extracts revealed characteristic differences between the tissues cultivated in light and dark. MALDI MS data show the presence of a precursor molecule and its mono- and tri-hydroxymethyl derivative, only in the cultures maintained in light. The relative amount of the different derivatives changed considerably, as a consequence of dimedone application in the culture medium and during the extraction.

Culture Techniques↗

PubMed1993

[Malignant tumor developing in transplanted tissue in the oral cavity (case report)].

Primary and metastatic malignant tumors appears frequently in the head and neck region. The occurrence of malignancies in tissues--transplanted to this area--are extraordinary rare. Authors report about a case, where the tumor developed in a cylindroid jump flap, used to the closure of the cleft palate. They discuss theoretical aspects, as well as the course of the disease.

Adult↗

PubMed1992