PubMed Health⌕ Search

Biomedical subjects

A Cör

Publications and source records attributed to A Cör.

At least 19 recordsLinked to original sources
PubMed2005

Microstructural analysis of implant-bone interface of hydroxyapatite-coated and uncoated Schanz screws.

The aim of the study was to compare the pin-bone interface microstructural characteristics of hydroxyapatite-coated (HAC) and stainless steel Schanz screws after 2, 4 and 6 months of implantation in a sheep model. The microstructure and composition of the hydroxyapatite coating were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Twelve coated and 12 uncoated screws were implanted into both femora of three sheep, each sheep receiving eight screws. Specimens of polished bone with screws were examined with SEM and light microscope for morphometric analyses. The HAC was approx. 40 microm thick, the grain size ranged from 5 to 40 microm, with pores less than 20 microm. The atomic ratio of Ca/P was 1.62. SEM showed that the bone-implant contact was better with HAC than with uncoated implants. The ingrowth of the bone in the HAC was clearly seen. Morphometric analysis showed good bone-implant contact in 65.1 (+/-24.6)% in the HAC and 32.0 (+/-23.3)% in the uncoated group (p<0.001). Although the percentage of good contact increased with time for both groups, it was significantly higher for HAC screws. Our investigation demonstrated a time dependent improvement of implant-bone contact of the HAC compared to standard stainless steel implants in the chosen experimental conditions.

Animals↗
PubMed2005

Expression of human telomerase catalytic protein in gallbladder carcinogenesis.

BACKGROUND: Telomerase catalytic subunit (hTERT) gene re-expression is a rate limiting step for the activity of telomerase, a key enzyme implicated in cellular immortalisation and transformation. AIMS: To determine the potential role of hTERT protein in gallbladder carcinogenesis. MATERIAL/METHODS: hTERT protein was analysed by means of immunohistochemistry in 89 gallbladder tissue samples: 16 normal epithelia, 14 reactive hyperplasias, 15 low grade dysplasias, 16 high grade dysplasias, and 28 adenocarcinomas. At least 200 nuclei were assessed for each slide and the mean number of positive signals for each nucleus was expressed as the hTERT index. RESULTS: The mean hTERT index increased progressively with the degree of gallbladder epithelial abnormalities: from 0.03 in normal epithelia, 0.04 in hyperplastic epithelia, 0.25 in low grade dysplasia, 0.82 in high grade dysplasia, to 0.93 in adenocarcinoma. Statistical analysis revealed that three different groups of gallbladder epithelial changes can be distinguished according to the number of hTERT signals for each nucleus: (1) normal and regenerative gallbladder epithelium, (2) low grade dysplasia, and (3) high grade dysplasia and adenocarcinoma (p < 0.001). CONCLUSIONS: The occasional presence of hTERT protein in normal and regenerative gallbladder mucosa reflects their regenerative capacity. Nevertheless, significantly higher hTERT indices in low and high grade dysplastic epithelia and in gallbladder adenocarcinomas are probably a consequence of hTERT re-expression--an early event in the multistep process of gallbladder carcinogenesis.

Adenocarcinoma↗
PubMed2004

Survivin expression is a negative prognostic marker in laryngeal squamous cell carcinoma and is associated with p53 accumulation.

AIMS: To investigate survivin expression in laryngeal squamous cell carcinoma (LSCC), its prognostic significance and relation to p53 status. Survivin is an inhibitor of apoptosis protein that is overexpressed in cancer. It has been implicated in both prevention of apoptosis and cell cycle regulation. It has been suggested that wild-type p53 represses survivin expression. METHODS AND RESULTS: Expression of survivin and p53 was analysed in 68 archival biopsy specimens of LSCC by immunohistochemistry. Survivin was detected in 67 of 68 LSCC cases; the proportion of survivin-positive cells varied from 8.2% to 100%. It was localized in the nucleus and/or cytoplasm of tumour cells. Of LSCC cases, 31.8% were p53+. The number of survivin-positive cells was significantly higher in the p53+ group. A high level of survivin expression and a supraglottic site of the tumour were two independent adverse prognostic factors in LSCC. CONCLUSIONS: Survivin is expressed in a varying proportion of cells in virtually all cases of LSCC. A high level of its expression predicts poor survival. Loss of wild-type p53 is a possible mechanism of survivin up-regulation in LSCC.

Antigens, Neoplasm↗
PubMed2002

Microdissection techniques for cancer analysis.

One difficulty in studying molecular changes of tumours has been the inability to isolate DNA and RNA from a homogeneous cell population. The combination of several new technologies should help overcome these hurdles. Microdissection is a technique for rapid and easy procurement of a pure cellular subpopulation away from its complex tissue milieu. Laser-assisted microdissection has recently been identified as a quick, simple and effective method by which microdissection of complex tissue specimens can be routinely performed for molecular analysis. With the advent of laser microdissection, cDNA libraries can be developed from pure cells obtained directly from stained neoplastic tissue, and microarrays of thousands of genes can now be used to examine gene expression in microdissected tumour tissue samples. This review will concentrate on the application of different microdissection techniques in the area of cancer research.

Cell Separation↗
PubMed2001

Proliferative and apoptotic activity in hepatocellular carcinoma and surrounding non-neoplastic liver tissue.

UNLABELLED: The aim of the study was to determine the proliferative and apoptotic activity of neoplastic and non-neoplastic hepatocytes, to ascertain whether there was a correlation between the histopathological characteristics of hepatocellular carcinoma (HCC) and its proliferative or apoptotic activity. METHODS: One tumour sample and one sample of non-neoplastic liver from 16 patients with HCC were analysed. The proliferative activity was established by immunohistochemical staining against PCNA (proliferating cell nuclear antigen) and Ki-67. Apoptotic activity was determined by morphological and TUNEL methods. Bcl-2 immunoreactivity was analysed. RESULTS: A positive correlation between PCNA and Ki-67 proliferative indexes was found in HCC (p < 0.01). The PCNA index was 0.21% +/- 0.80% (Mean +/- SD) in non-neoplastic liver and 7.41% +/- 8.22% in HCC, while the Ki-67 index was 0.19% +/- 0.26% in non-neoplastic liver and 9.67% +/- 7.70% in HCC. The differences between HCC and non-neoplastic liver were significant (p < 0.05). The PCNA index differed significantly between different HCC grades (p < 0.05). In HCC and non-neoplastic liver samples, apoptotic indexes (AI) assessed morphologically were higher than Al determined by the TUNEL method. Differences in Al (irrespective of the method used) between different HCC grades were not significant. Bcl-2 staining was positive in one non-neoplastic liver sample (6.3%) and in 4 HCC samples (25%). CONCLUSIONS: PCNA and Ki-67 were useful for proliferative activity assessment of hepatocytes. There were no differences in apoptotic activity between HCC and non-neoplastic tissue, so it seems that uncontrolled tumour cell division plays an important role in HCC growth. In the regulation of the apoptotic process in HCC, Bcl-2 could be important.

Apoptosis↗
PubMed2001

Isolation of polyacetal wear particles from periprosthetic tissue of isoelastic femoral stems.

We analysed revised Mathys isoelastic polyacetal femoral stems with stainless-steel heads and polyethylene acetabular cups from eight patients in order to differentiate various types of particle of wear debris. Loosening of isoelastic femoral stems is associated with the formation of polyacetal wear particles as well as those of polyethylene and metal. All three types of particle were isolated simultaneously by tissue digestion followed by sucrose gradient centrifugation. Polyacetal particles were either elongated, ranging from 10 to 150 microm in size, or shred-like and up to 100 microm in size. Polyethylene particles were elongated or granules, and were typically submicron or micron-sized. Polyacetal and polyethylene polymer particles were differentiated by the presence of BaSO4, which is added as a radiopaque agent to polyacetal but not to polyethylene. This was easily detectable by back-scattered SEM analysis and verified by energy dispersive x-ray analysis. Two types of foreign-body giant cell (FBGC) were recognised in the histological specimens. Extremely large FBGCs with irregular polygonal particles showing an uneven, spotty birefringence in polarised light were ascribed to polyacetal debris. Smaller FBGCs with slender elongated particles shining uniformly brightly in polarisation were related to polyethylene. Mononucleated histiocytes containing both types of particle were also present. Our findings offer a better understanding of the processes involved in the loosening of polyacetal stems and indicate why the idea of 'isoelasticity' proved to be unsuccessful in clinical practice.

Adult↗
PubMed2000

Morphology of FRTL-5 cell colonies in a semi-solid medium.

For the first time, 3, 7 and 10 days growth of normal thyroid follicular FRTL-5 cell colonies in a semi-solid medium of 0.6% methocel over 1% agar base was morphometrically analyzed. It was found that the areas of FRTL-5 colonies as well as their perimeters and maximum diameters increased, while according to their form factors the FRTL-5 colonies were regular in shape. After 10 days in a semi-solid medium, 83% of the FRTL-5 colonies had maximum diameters greater than 50 microm. It is obvious that after long culturing of FRTL-5 cells under the influence of the pituitary thyroid-stimulating hormone (TSH) these cells are not uniform anymore and that they grow in a semi-solid medium.

Animals↗
PubMed2000

Chromosomes 7,17 polysomies and overexpression of epidermal growth factor receptor and p53 protein in epithelial hyperplastic laryngeal lesions.

PURPOSE: To visualize directly a sequence of genetic changes underlying the entire spectrum of epithelial hyperplastic laryngeal lesions (EHLL) and laryngeal cancer by the use of non-isotopic in situ hybridization (ISH) for chromosomes 7 and 17 in correlation with overexpression of p53 protein and epidermal growth factor receptor (EGFR). The specific aim was to compare the results and prognostic significance between the two types of EHLL: isolated, mainly atypical hyperplasia or risky epithelium, and EHLL associated with squamous cell carcinoma (SCC). PATIENTS AND METHODS: 59 tissue specimens of EHLL obtained from 34 patients, graded according to the Ljubljana classification into simple (SH), abnormal (AbH) and atypical hyperplasia (AtH), and carcinoma in situ (CIS) were included in the study. Non-fluorescent ISH for chromosomes 7 and 17 was performed by biotinylated alpha-satellite DNA probes. Immunohistochemical staining for EGFR and p53 protein was analyzed on the same tissue samples. RESULTS: Polysomy for both chromosomes increased in correlation with progressive grades of EHLL. The most important finding was the statistically significant difference in chromosome copy numbers between the isolated AtH and AtH associated with SCC. Overexpression of EGFR and p53 protein was found in 61 (36/59) and 52% (31/59) of cases, respectively. The immunoreactivity for both markers increased with the grade of lesions, but the staining pattern was not so uniform in isolated EHLL. On the other hand, the immunoreactivity was expressed more constantly in EHLL adjacent to SCC. CONCLUSIONS: Numerical changes in chromosomes 7 and 17 might be associated with an upregulation of EGFR and p53 genes, and could contribute to critical events in laryngeal carcinogenesis. For daily practice, the cytogenetic and immunohistochemical analyses could be of assistance in distinguishing between low- and high-risk groups of AtH. However, the isolated forms of atypical hyperplasia need considerable further study by evaluating genetic changes with the described methods regarding their ultimate transformation to carcinoma.

Adult↗
PubMed2000

Extensive metallosis and necrosis in failed prostheses with cemented titanium-alloy stems and ceramic heads.

We describe three prostheses with cemented titanium-alloy stems and Al2O3 ceramic femoral heads which had to be revised after a mean period of implantation of 78 months. In each case, the neck of the prosthesis had been so severely worn that the profile was elliptical rather than circular. There was severe metallosis of the periprosthetic tissues. Metal particles isolated from the tissues were approximately one nanometre in size and the ratios of titanium, aluminium and vanadium in the particles were the same as in the original alloy. Histologically, the high concentration of metal particles masked the presence of high-density polyethylene (HDP) debris, but again particles about one nanometre in size were isolated from the tissues. The severe necrobiosis and necrosis noted were consistent with other reports of the presence of extensive wear particles in periprosthetic tissues. Wear is presumed to have occurred as a result of mismatch between the shape or size of the taper cone and the femoral head, or to changes in the geometry of loading due to migration of the cup. To facilitate early intervention, patients with this design of prosthesis should be monitored radiologically.

Aged↗
PubMed2000

Morphometry of the FRTL-5 cells after irradiation.

The morphological changes of in vitro irradiated FRTL-5 cells and their ability to grow in semi-solid medium were studied morphometrically. FRTL-5 cells were grown in medium with 4 different concentrations of TSH (0, 0.1, 1, 10 mU/ml). After irradiation with 0 Gy, 2 Gy and 4 Gy, the cells were seeded on glass cover-slips and in methocel. Fourteen days after irradiation, the morphometric analysis of FRTL-5 cells and their nuclei was performed. The results showed that irradiation and different doses of TSH have influence on FRTL-5 cell size, more on their nuclei than on the cells as a whole. Growing of FRTL-5 cells in the methocel indicates the possible transformation of these cells after long-culturing in the TSH medium and after irradiation.

Animals↗
PubMed1999

Proliferative activity of Hürthle cell thyroid tumours.

To improve our understanding of the basic biological mechanisms of Hürthle cell tumours (HCT), proliferative activity in 20 HCT was determined by Ag-NOR (nucleolar organiser regions) counting and by immunohistochemical markers proliferating cell nuclear antigen (PCNA) and MIB-1. Ten surgically removed Hürthle cell adenomas (HCA) and 10 Hürthle cell carcinomas (HCC) were used for the study. For comparison, a group of 10 thyroid adenomas without Hürthle cells (SA) was also evaluated. There were significant differences in the percentages of PCNA- and MIB-1-positive nuclear areas between HCA and HCC as well as between SA and HCA. The mean number of Ag-NORs per nucleus showed no significant differences between our groups. However, determination of percentages with 5 or more Ag-NORs per nucleus within one focal plane of sections was more useful for the differentiation between thyroid tumours included in our study. The combination of three types of cell kinetic markers may provide insight into the still poorly understood relationships among karyological abnormalities, enhanced proliferation speed, clonal expansion and invasiveness of HCT.

Adenocarcinoma↗
PubMed1999

Effect of pH on Ki-67 antigen retrieval in renal cell carcinoma.

The efficacy of Ki-67 antigen retrieval (AR) was assessed in 20 formalin fixed-paraffin embedded specimens of renal cell carcinoma using three solutions with different pH values. The AR was performed by means of microwave oven heating up to 97 degrees C for 15 minutes. Better results were obtained using solutions with pH values 8.0 and 9.9 compared with AR in a solution of pH 6.0, which is routinely used in daily pathological practice. Individual testing of various AR conditions is recommended to obtain the best immunohistochemical results.

Carcinoma, Renal Cell↗
PubMed1998

The effect of irradiation on FRTL-5 cell morphology.

The morphological changes and proliferative activity of FRTL-5 cells irradiated in vitro with one dose of 0, 8, 12, 16, 24 or 32 Gy were studied morphometrically 7, 14 and 21 days after irradiation. The number of cells irradiated with 24 Gy and 32 Gy decreased during the 3 weeks of the experiment. Morphometrical analysis confirmed that the cells repaired their injuries up to 16 Gy of irradiation, while doses of 24 and 32 Gy damaged them irreversibly. Thyroglobulin was detected in cells after all doses of irradiation.

Animals↗
PubMed1997

Quantitative pathology of laryngeal epithelial hyperplastic lesions.

We studied 40 laryngeal biopsies samples in order to ascertain the reliability of light microscopical criteria for subdividing laryngeal epithelial hyperplastic lesions (EHL) and carcinoma in situ as well as to determine the relationship between proliferative activity of their epithelial cells and the histological grade. The biopsies were divided into four groups in accordance with the Kambic-Lenart classification: simple, abnormal and atypical hyperplasia and carcinoma in situ. 10 cases in each group were included. The morphometrical analysis was carried out by a semiautomatic image analysis system. The proliferative activity was determined by the high percentage of cell nuclear antigen (PCNA) and Ki-67 positive epithelial cells and with counting nucleolar organizer regions (Ag-NORs) per nucleus. Our results suggest that measuring the nuclear area of the basal cells. augmented with basaloid cells and carcinomatous cells, is the most useful morphometrical method of differentiating three types of laryngeal EHL and carcinoma in situ, while the proliferative activity progressively increased with the degree of epithelial hyperplasia. Morphometrical methods and proliferative activity should be regarded as useful in conjunction with the traditional histopathological methods allowing more of objective grading of EHL.

Biopsy↗
PubMed1997

Langerhans and other immunocompetent cells in vocal cord epithelial hyperplastic lesions of patients with chronic laryngitis.

The aim of the study was to evaluate the intraepithelial and stromal density of Langerhans cells and lymphoid infiltrate in different stages of carcinogenesis in vocal cord biopsies of 24 randomly selected patients with chronic laryngitis. The Langerhans and lymphoid cells were counted using immunolabelling with antibodies against CD1a, S100, CD3, CD20, and CD68 on paraffin-embedded sections of 24 archival laryngeal vocal cord mucosa biopsy specimens, 6 classified as simple, 7 as abnormal, and 11 as atypical epithelial hyperplasia. Results were statistically evaluated using the Kruskal-Wallis and Wilcoxon sign rank tests. The mean number of Langerhans cells and T lymphocytes per mm2 of cross-sectioned epithelium was found to increase from simple to atypical hyperplasia. There were statistically significant differences in Langerhans cell density between atypical hyperplasia and each of the other 2 grades, simple and abnormal hyperplasia, with p < 0.05. Our study suggests the involvement of immune mechanisms, particularly cell mediated, during laryngeal carcinogenesis and the possibility that the assessment of Langerhans cell density might be of prognostic significance.

Adult↗
PubMed1997

Langerhans cells in human papillomaviruses types 6/11 associated laryngeal papillomas.

Some studies have shown a reduced density of Langerhans cells (LCs) within epithelium infected by human papillomaviruses (HPV) types 16/18. However, data on a correlation between HPV types 6/11 infection and LCs have been missing. To solve this problem, we analysed 24 biopsy specimens of laryngeal papillomas, selected randomly, 20 multiple and 4 solitary. The presence of HPV 6 and 11 was proven by polymerase chain reaction (PCR) using 2 different sets of primers in 23 biopsy specimens. Abnormalities of the covering stratified squamous epithelium were graded according to the Kambic-Gale classification. LCs were immunohistochemically labelled with 2 different antibodies, CD1a and S100. Quantitative analysis was performed to determine the density of LC per mm2 in different grades of epithelial abnormalities covering laryngeal papillomas. Although no statistically significant differences in the mean number of LCs per mm2 of the cross-sectioned epithelium covering laryngeal papillomas were observed comparing simple, abnormal and atypical hyperplasia groups, the mean number of LCs per mm2 in laryngeal papillomas associated with HPV types 6/11 infection substantially exceeded that of the vocal cord surface epithelium in patients with chronic laryngitis.

Adolescent↗
PubMed1997

Epidermal growth factor receptor, c-erbB-2 and p53 overexpressions in epithelial hyperplastic lesions of the larynx.

An immunohistochemical analysis of overexpression of epidermal growth factor receptor (EGFR), c-erbB-2, and p53 proteins was performed on 43 biopsies of laryngeal epithelial hyperplastic lesions (EHLL), classified according to the Kambic-Lenart classification, and in 11 cases of laryngeal carcinoma (SCCL). The aim of the present study was to determine whether there is a correlation between the staining patterns of these proteins and different grades of EHLL, and to reveal their possible prognostic value. We compared the staining patterns of atypical hyperplasia adjacent to cancer with the same type of lesions which have not turned malignant. p53 and EGFR overexpressions were detected in 28/54 (52%) and 33/54 cases (61%), respectively, and tend to increase with the degree of epithelial changes. The intensity of staining in various grades of EHLL adjacent to cancer was more pronounced than the same type of lesions which have not progressed to cancer. c-erbB-2 was weakly positive in the majority of cases, and changed from predominantly membranous in simple hyperplasia to cytoplasmic staining in abnormal and atypical hyperplasias. There was no significant statistic correlation between the amount of positive cells for all proteins and the grade of epithelial abnormalities. We conclude that the overexpression of each biomarker itself adds little predictive value over routine histomorphology, and cannot be regarded as a reliable prognostic factor for EHLL. However, the histologic characteristics of atypical hyperplasia together with the immunostaining patterns of EGFR and p53 up to two-thirds or more of the epithelial thickness could be considered a reliable pattern which correlates with the progression to cancer.

Carcinoma, Squamous Cell↗