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Biomedical subjects

C Hegedüs

Publications and source records attributed to C Hegedüs.

At least 19 recordsLinked to original sources
PubMed2001

Accuracy of in vivo carotid B-mode ultrasound compared with pathological analysis: intima-media thickening, lumen diameter, and cross-sectional area.

BACKGROUND AND PURPOSE: This study aimed to determine the correlation of in vivo ultrasound measurements of intima-media thickening (IMT), lumen diameter, and cross-sectional area of the common carotid artery (CCA) with corresponding measurements obtained by gross pathology and histology. METHODS: Sixty-six moribund neurological patients (mean age 71 years) underwent B-mode ultrasound of the CCA a few days before death. During autopsy, carotid specimens were removed in toto. Carotid arteries were ligated and cannulated for injection of a hydrophilic embedding material under standardized conditions. The carotid bifurcation was frozen and cut manually in 3-mm cross slices. Digital image analysis was carried out to determine the diameter and the cross-sectional area of the frozen slices of the CCA. IMT was assessed by light microscope. Ultrasonic and planimetric data were compared. RESULTS: Mean measurements of lumen diameter and cross-sectional area were 7.13+/-1.27 mm and 0.496+/-0.167 cm(2), respectively, by ultrasound, and 7.81+/-1.45 mm and 0.516+/-0.194 cm(2), respectively, by planimetric analysis of the unfixed redistended carotid arteries (R(2)=0.389 and 0.497). The mean IMT was 1.005+/-0.267 mm by ultrasound and 0.67+/-0.141 mm histologically, resulting in a mean difference of -31%. CONCLUSIONS: Transcutaneous B-mode ultrasound provides a reliable approach for in vivo measurements of the cross-sectional area and, less exactly, of the lumen diameter of the CCA. Compared with histological results, in vivo ultrasound measurements of the IMT are systematically larger.

Adult↗
PubMed1999

An atomic force microscopy study on the effect of bleaching agents on enamel surface.

OBJECTIVES: The aim of the present study was to evaluate the effect of three peroxide-containing bleaching agents, Opalescence, Nite White and a 30% hydrogen peroxide solution, on enamel surfaces using Atomic Force Microscopy (AFM). METHODS: Fifteen non-carious human incisors (ten maxillary and five mandibular, extracted for periodontal reasons) were used. The teeth were divided randomly into three groups of five, according to the bleaching agents. The labial surface of each tooth was imaged by AFM before and after treatment. Each bleaching agent was applied for a total of 28 h (in individual 4 h treatments). The specimens were examined only after 28 h of treatment. RESULTS: On comparing the AFM images of untreated and treated enamel, surface alterations were observed after 28 h of treatment with Opalescence, Nite White and 30% hydrogen peroxide solution. Several grooves present in the enamel surface of untreated teeth became deeper after the bleaching procedure. The depths of the grooves increased in each case. The increase in the depth of grooves was more pronounced in the case of the 30% H2O2 solution. CONCLUSION: Home-use bleaching agents are capable of causing enamel surface alterations. It is hypothesized that the peroxide-containing bleaching agents affect the organic phase of enamel. Peroxides can affect not only the surface but also the inner structure of enamel. As a result of its low molecular weight, hydrogen peroxide can penetrate into the enamel. Thus, inner oxidative effects are more likely to occur in the subsurface enamel where more organic material is present and oxidation is capable of altering the outer enamel and the surface.

Acrylic Resins↗
PubMed1999

[Interface between Ni-Cr alloy and ceramic studied by scanning electron microscopy].

In this investigation we observed the interface between Wiron 99 (Bego) dental Ni-Cr alloy and Vision (Wohlwend AG) ceramic opaquer with SEM. In the system there are intermediate phases coming from a solid phase rection which play an essential role in the metal-ceramic bond. The analytical methods showed that in this phases the content of Ni and Cr charge not monotonously from alloy to ceramic which shows strong chemical effects (the selective affinity of Cr and Ni). The concentration of Cr after the alloy surface increases in a 1-1.5 microns layer, where its concentration is higher than at the alloy, while the concentration of Ni decrease in this layer. Than at the ceramic side of the reaction zone the concentration of Ni increases in a 1-1.5 microns wide layer where its concentration is near upon that one in the alloy.

Ceramics↗
PubMed1997

[Typical symptoms of methyl acylate sensitivity in wearers of acylate dentures].

Between 1986. and 1995. 150 patients were patch tested who had developed allergic reactions to their prosthesis made from acrylate. Three patients are described, whose history and patch test results confirmed the hypersensitivity to methylmetacrylate. The typical symptoms of acrylate sensitivity are discussed. After the removal of acrylate prosthesis and replacement with polyamide base (Valplast) prosthesis, the symptoms disappeared. Because the number of allergic reactions increases, the authors emphasize the necessity of prescreening in suspected cases of acrylate allergy.

Acrylates↗
PubMed1995

[Computer tomography in implantology].

During the planning of implantation the CT method helps in determining the location of the implant and aids in choosing the right implant. It provides the following measurable information about the jaw-bones: height and width; exact location of bone deficiencies; the orovestibular shape of the alveolar process; the course of the mandibular canal; the location of the mental foramen; the location and size of the canalis incisivus; the area of the nasal cavity and the maxillary sinus; the quality of the bones and the relationship between cortical and spongious bone. In comparison to the X-ray examinations possession of these informations increase significantly the safety of planning before surgery.

Dental Implantation↗
PubMed1994

[Contact allergy reactions to Silodent impression material].

The silicon based impression materials are often used in dental practice. Recently, we have observed two cases of contact allergic reaction after using Silodent (Ferrokémia) impression material. Epicutaneous test has shown that the allergic reaction is provoked by the catalisator. This hypersensitivity reaction is due to a previous sensibilization (e.g. previous impression taking or environmental hazards). No epicutaneous reaction to the other types of silicon based impression materials was found.

Adult↗
PubMed1992

[The effect of surface etching on tensile strength].

The aim of this study was to investigate the effect of different partial size of corundum used by sand blasting on the surface roughness and on the tensile strength. The conclusions of the authors were as follows: 1. The maximum values of tensile strength were measured when 200-250 microns corundum was used. 2. The values of the R(a) and Rmax were grown proportionally with the grain of corundum, but it was not resulted in the same increase of the tensile strength. 3. After the tensile test the residue of the bonding agent on one surface of the test-piece pairs, always remained significantly higher, than on the other, but this phenomenon cannot be explained by the differences between R(a) and Rmax within the test-piece pairs.

Acid Etching, Dental↗
PubMed1989

[Liver changes suggesting alpha-1-antitrypsin deficiency (a neglected disease)].

Liver needle biopsies of one hundred infants and children were examined. In fifteen of them the liver was normal. Of the 85 patients with liver disease three had liver changes due to severe alpha-1-antitrypsin (AAT) deficiency. In two cases fibrosis and inflammation of the portal fields could be seen. In the third case in addition to portal fibrosis and moderate periportal inflammation paucity of the intrahepatic bile ducts was found. Characteristic PAS-positive diastase resistant hepatocellular globules occurred only in one case but, using immunoperoxydase method, periportal hepatocytes showed AAT positivity in all three infants. Of 830 adult patients with liver cirrhosis 8 had PAS-positive diastase resistant AAT immunoreactive globules in the periseptal hepatocytes suggesting AAT deficiency, however, the serum AAT level and the phenotype of them were unknown. Investigation for AAT deficiency should be carried out in children and young adults with a history of neonatal liver disease and possibly in all patients with liver disease of uncertain etiology, especially in those with PAS-positive, AAT immunoreactive hepatocellular globules.

Biopsy↗
PubMed1989

Ultrastructure of the Ito cells in liver disease associated with fibrosis.

The ultrastructure of Ito cells was examined in percutaneous needle liver biopsies of 36 patients. In three cases the liver was normal. Four specimens showed mild or moderate fatty degeneration. In the rest of the liver samples various types of fibrosis were seen: in four cases portal, in ten centrilobular, in eight periportal fibrosis and in five cases cirrhosis. In the normal liver Ito cells occurred not only in the Disse spaces but also in the walls of the terminal hepatic venules. In livers showing portal fibrosis the ultrastructure of Ito cells was similar to that seen in the normal liver. In the fibrotic areas of liver samples showing centrilobular or periportal fibrosis or cirrhosis Ito cells localized inside the fibrotic tissue and along the border between the connective tissue and hepatocytes. These interstitial Ito cells contained few lipid, abundant rough endoplasmic reticulum with dilated tubules filled by a flocculant material, well developed Golgi complexes and often bundles of 5 nm thick filaments with densities. These cells also known as activated Ito cells were in places surrounded by immature collagen fibrils and basement membrane fragments. There was a close contact between activated Ito cells and lymphocytes. The ultrastructure of Ito cells localizing in non-fibrotic areas did not differ from that seen in normal liver lobules. These observations suggest that Ito cells are related to fibroblasts and myofibroblasts and play an important role in the pathogenesis of liver fibrosis in humans.

Biopsy, Needle↗
PubMed1989

[Ultrastructure of Ito cells in fibrotic liver diseases].

Authors have studied the ultrastructure of Ito-cells in percutane needle-biopsy samples of hepatic tissue from 36 patients. In 3 samples no alteration was found, in four only moderate steatosis occurred without fibrosis. In four samples portal, in ten centrilobular and in five periportal fibrosis was detected, while in five samples cirrhosis was pointed out. In the intact liver, Ito-cells occur not only in the spaces of Disse but also in the wall of the central vein. In portal fibrosis Ito-cells were similar in location and structure to those in the non-fibrotic liver. In centrilobular and periportal fibroses as well as in cirrhosis Ito-cells in the fibrotic parenchyma areas were either localized in the accumulated connective tissue or at the border of connective tissue and hepatocytes. These interstitial Ito-cells contained small amount of lipid, abundant dilated rough endoplasmic reticulum filled with a flocculent material, well-developed Golgi-complex and often bundles of 5 nm thick filaments with dense territories. Close to the Ito-cells immature collagen-fibrils and basement membrane-fragments were seen. A close relationship was pointed out between activated Ito-cells and lymphocytes. In parenchyma areas away from fibrotic foci the structure of Ito-cells was comparable to that of Ito-cells in intact hepatic lobules. Observations suggest that Ito-cells are related to fibroblasts and myofibroblasts and play a role in the pathogenesis of fibrosis occurring in human liver diseases.

Cytoplasm↗
PubMed1989

[Comparative study of the sealing properties of retrograde amalgam root fillings using a microtechnic and the naked eye].

The aim of the present investigation was to compare the quality of retrograde amalgam fillings made under the control of the naked eye and that of a stereomicroscope. The 58 extracted upper incisors used for study had been divided into two groups and were filled with one of the control methods. In both groups on 25 teeth the microleakage was assessed by dye diffusion, the surfaces of the remaining 4 teeth were subjected to SEM examination. The depths and angle belonging to the stained sections of the perimeter had been measured under a stereomicroscope with a magnification of 40 and the area affected was calculated. Significantly (p less than 0.001) less area was involved in the stereomicroscopic group (1.46 +/- 0.34 mm2) than in the naked eye group (3.89 +/- 1.80 mm2). The SEM photographs demonstrated the faults which can be eliminated by the use of a stereomicroscope and showed also those which derive from the physical and chemical properties of the amalgam.

Dental Amalgam↗
PubMed1984

A case of liver cirrhosis with alpha-1-antitrypsin globules and hepatitis B surface antigen seropositivity.

PAS staining, immunohistochemical examination and electron microscopy revealed presence of alpha-1-antitrypsin (AAT) globules in the hepatocytes of a HBsAg and anti-HBc seropositive female patient diseased of liver cirrhosis. The possible causes of cirrhosis are briefly analysed and the diagnostic importance of PAS-positive, amylase-resistant hepatocellular inclusions is discussed. Apart from the case reported, only two of 509 cirrhotic livers of adults, examined either by biopsy or post mortem, demonstrated similar characteristic PAS-positive globules. This indicates that in the population group (135,000 persons) referred for health care to the hospital where the examinations were done, AAT deficiency has played a negligible role in the development of liver cirrhosis in adults.

Female↗
PubMed1981

Growth of human colorectal tumor xenografts in immunosuppressed mice reconstituted with normal cells.

The growth of human colorectal tumor xenograft lines was studied in immunosuppressed mice after reconstitution with sensitized and nonsensitized macrophages, thymocytes and splenocytes obtained from normal mice. Intravenously injected macrophages caused temporary inhibition of tumor growth. This effect needed intact cells and was independent from the presence of the spleen. The weight of spleen increased in normal mice sensitized with xenograft tumor, and the sensitized splenocytes injected into tumor-bearing immunosuppressed mice caused substantial tumor-growth delay.

Animals↗