Mean Number Of AgNORs Research Articles

Komparativna evaluacija parametara argirofilnih regiona jedarnog organizatora kod benignih i malignih tumora dojke

Aim. The aim of the paper was to evaluate the AgNOR parameters for the discrimination of benign from malignant breast tumors via a new approach - the total AgNOR area/nuclear area (TAA/NA). Material and methods. Three groups, consisting of control (n = 14), benign (n = 18) and malignant (n = 28) participants were included in the study. The AgNOR staining technique was performed and both mean AgNOR number and TAA/NA ratio were evaluated. Results. While the differences between the control and patient groups were statistically significant for AgNOR number (p < 0.001), it was not significant between the malignant group and the benign group for mean AgNOR number (p > 0.05). For the ratio of TAA/NA, the differences between the control and benign group (p < 0.001), control and malignant group (p < 0.001), and malignant and benign patient groups were significant. (p < 0.05). Conclusion. We consider that the evaluation of the TAA/NA rate, when compared with the AgNOR number, can be more sensitive and useful tool for distinguishing benign from the malignant breast lesions.

Arjirofilik Nükleolar Organize Edici Bölgeler Non ST Elevasyonlu Miyokard İnfarktüsünde Hipoksik Yanıtın Yeni bir Belirteci Olabilir mi?

Objective: Non-ST elevation myocardial infarction (NSTEMI) is a type of acute coronary syndrome and its’ incidence is similarly high to ST-elevation myocardial infarction. Nucleolar organizing regions (NORs) are located of the secondary structure of acrocentric chromosome and composed of proteins and ribosomal DNA (rDNA) some of which are argyrophilic. We aimed to investigate the change of AgNOR proteins, which increase in hypoxia, in patients with NSTEMI.
 Methods: A total of 125 participants, 63 patients with NSTEMI and 62 volunteers without any acute coronary syndrome were included in the study. Echocardiography was performed and both mean AgNOR Number and total AgNOR area/total nuclear area (TAA/TNA) were detected for each individuals.
 Results: The mean AgNOR number and TAA/TNA ratio were significantly higher in the NSTEMI group than control (p

Argyrophilic Nucleolar Organizer Regions as New Biomarkers in ST-Elevation Myocardial Infarction.

(1) Background: ST-elevation myocardial infarction (STEMI) is an inflammatory disease in which neutrophils, macrophages, and lymphocytes accumulate in the ischemic myocardium and have important functions. Nucleolar-organizing regions (NORs) are the site of the ribosomal genes composed of ribosomal DNA and proteins. We aimed to evaluate AgNOR proteins, which have never been studied in patients with STEMI in the literature. (2) Methods: A total of 140 participants (75 with STEMI and 65 volunteers without any diagnosis of acute coronary syndrome) were included in this study. Echocardiography was carried out, and mean AgNOR number and total AgNOR area/total nuclear area (TAA/TNA) were evaluated for all individuals. (3) Results: The mean AgNOR number and TAA/TNA ratio were significantly higher in the STEMI group than the control (p < 0.001). Statistically significant relations between both TAA/TNA ratio and mean AgNOR number and interventricular septal thickness, fasting blood sugar, creatinine, HDL, hemoglobin (g/dL), WBC (µL/mL), monocytes, neutrophils, and neutrophil/lymphocyte ratio were detected (p < 0.05). Moreover, a statistically significant relation between LDL (mg/dL) and mean AgNOR number (p = 0.005) was detected. (4) Conclusion: Both AgNOR protein amounts increase depending on the hypoxia that occurs in STEMI. The AgNOR proteins may thus be promising markers in STEMI.

May Argyrophilic Nucleolar Organizer Regions Be Used as a Biomarker for the Detection of the Degree of Ischemic Damage Instead of Tunel in Testicular Torsion?

Background and Objectives: It is of great importance to obtain information about the severity of ischemic damage and duration of testicular torsion for an effective treatment strategy. Nucleolar-organizing regions (NORs) are sites of the ribosomal genes composed of ribosomal DNA and proteins. Post-silver staining NORs are termed “AgNOR”. Since AgNORs clearly reveals the self-renewal potential of cells damaged in ischemic events, we performed the current study. Materials and Methods: The study was carried out in four groups as control, sham, early, and late T/D. In the surgical groups, testes were corrected after a 4-h ischemia period. Testicular tissue samples were taken on the third day after detorsion in group 1, 2, 3, and on the tenth day after detorsion in group 4. TUNEL and silver stainings were applied to all samples. Results: The differences were significant among the groups for both mean AgNOR number and total AgNOR area/total nuclear area (TAA/TNA). Moreover, the differences between control and early torsion-detorsion (T/D), between control and late T/D, between sham and early T/D, between sham and late T/D, and between early T/D and late were statistically significant for AgNOR amount. Furthermore, statistically significant differences among the groups for an average number of apoptotic cells per tubule and the percentage of apoptotic tubule values were detected. Discussion: The apoptotic index gives the ratio of cells that are damaged and will die in a programmed way and cells that remain intact, rather than show the viability of the returning testicle. However, by measuring cells that regenerate with AgNOR, we can show not only those that survive but also cells that can repair themselves. Conclusion: AgNOR proteins are usable for the early observation of ischemic injury levels. The amount of AgNOR protein can enlighten us about the extent of testicular damage after T/D treatment. It may also help the physician in the development of effective treatment strategies for cases.

Testis Torsiyonunda Rapamisin Tedavisinin Antioksidan Enzim Değişiklikleri ve AgNOR Üzerindeki Etkilerinin Değerlendirilmesi

Objective:Testicle torsion/detorsion cause ischemia. Rapamycin has immune suppressive and antioxidant defense mechanisms. Nucleolar-organizing regions(NORs) are loops of ribosomal DNA. Methods: To evaluate mean AgNOR number and total AgNOR area/total nuclear area(TAA/TNA) ratio and the relation between these proteins and rapamycin in the Torsion/Detorsion process of testes. The six groups as control, sham, early and late torsion-detorsion (ETD&amp;lt;D) groups, and early and late rapamycin treatment groups (ETD+R&amp;lt;D+R) were included. The TAA/TNA and mean AgNOR number of testes cells and biochemical analysis of GPx, SOD, and TBARS activities were detected. Results: Significant differences were detected among the groups for mean AgNOR number and TAA/TNA(p&amp;lt;0.05). For both mean AgNOR number and TAA/TNA, significant differences were found between control and ETD, between control and ETD+R, between control and LTD, between control and LTD+R. Also, a statistically significant relationship between both mean AgNOR numbers and TAA/TNA of testes cells and all the antioxidant enzymes (SOD, TBARS, and GPX) were detected(p&amp;lt;0.05). Conclusion: We may obtain information about the levels and duration of testes injury considering the levels of these proteins. Thus it can be said that these proteins may be used in the development of new and more effective therapeutic approaches to prevent the negative effects of T/D injury.

Does capsaicin have therapeutic benefits in human colon adenocarcinoma? Selection of the most reliable dose via AgNOR

Background/aim To determine the effect of different doses of capsaicin on AgNOR protein synthesis in human colon adenocarcinoma derivate from colon cancer (Caco-2 cell).Materials and methods In this experimental study, after the cultured of Caco-2 cell line, the cells are divided into 4 groups as control and different capsaicin exposed doses (25uµ, 50uµ, and 75uµ). Mean AgNOR number and total AgNOR area/nuclear area (TAA/NA) were calculated.Results A significant differences were detected between control and capsaicin (50uµ) (P = 0.001), between control and capsaicin (75uµ) (P = 0.000), between capsaicin (25uµ) and capsaicin (50uµ) (P = 0.001) and between capsaicin (25uµ) and capsaicin (75uµ) (P = 0.000) for TAA/NA. Also, there were significant differences between control and capsaicin (50uµ) (P = 0.001), between control and capsaicin (75uµ) (P = 0.000), between capsaicin (25uµ) and capsaicin (50uµ) (P = 0.000) and between capsaicin (25uµ) and capsaicin (75uµ) (P = 0.000) for mean AgNOR number.Conclusion: A certain amount of capsaicin has a protective effect against colon adenocarcinoma and the dose concentrations are important for the most reliable treatment.

Determination of Proliferative Activity of Neoplastic Cells by Ki67 and AgNOR Staining in Ovine Pulmonary Adenocarcinoma Affected Lungs

Ovine Pulmonary Adenocarcinoma (OPA) is a natural lung cancer of the sheep caused by Jaagsiekte Sheep Retrovirus (JSRV). In the present study, 17 OPA affected lung samples were subjected to histopathological, histochemical and immunohistochemical studies. Grossly, lungs revealed diffuse areas of consolidation or tumor nodules and histologically lung sections showed proliferation of alveolar epithelial cells that were arranged in papillary or acinar pattern. The lung sections were further subjected to immunohistochemical staining for cytokeratin and Ki-67. The proliferative activity of tumor cells was determined by Ki67 and AgNor staining and the mean value of Ki-67 index was 9.53 + 1.88. The mean number of AgNORs for all the cases ranged from 6.5 to 11.9 with a mean + standard deviation values of 9.2 + 1.2. The mean values of Ki-67 index and AgNOR staining were increased in the sections of lung tumor than the normal lung sections indicating the increased proliferative activity of lung tumor epithelial cells.

May argyrophilic nucleolar organizing region-associated protein synthesis be used for selecting the most reliable dose of drugs such as rhamnetin in cancer treatments?

Rhamnetin is a flavonoid that has antioxidant, anti-inflammatory and anti-cancer effects. Nucleolar-organizing regions are the ribosomal genes region. We aimed to identify whether rhamnetin has an effect on cell proliferation and whether AgNOR proteins may be used for the detection of therapeutic benefits of the drugs and new metabolites, which have the potential of being used for cancer treatments. Twenty-four mice with Ehrlich's ascites carcinoma (EAC) were randomly assigned to three main groups as positive control, and groups 2 and 3 treated intraperitoneally with rhamnetin (100 µg/kg and 200 µg/kg, respectively). All the animals were sacrificed on day16, 24 h after the last dose; the tumors, which developed at the site of injection were removed. Then, mean AgNOR number and total AgNOR area/nuclear area (TAA/NA) were detected for each mouse. Significant differences were detected among all groups for mean AgNOR number (p = 0.000) and TAA/NA ratio (p = 0.000). While the difference between positive control and Rhamnetin (100 µg/kg) group was not significant (p = 0.387), there are significant differences between positive control and Rhamnetin (200 µg/kg) group (p = 0.000) and between Rhamnetin (100 µg/kg) and Rhamnetin (200 µg/kg) groups (p = 0.000) for TAA/NA ratio. Rhamnetin has an important role in preventing cancer formation. Our study showed that mean AgNOR numbers and TAA/NA values may be used also as biomarkers for evaluating the success rate of the performed therapeutic strategy and accurate dose selection for the management of the disease (Tab. 3, Fig. 3, Ref. 45).

The detection of curcumins' antitumoral effects via argyrophilic nucleolar organizing region-associated protein synthesis in mice with ehrlich's ascitic carcinoma.

Curcumin is a polyphenol compound that has antioxidant, anticancer, anti-inflammatory, anti-hyperlipidemic and antimicrobial effects. Nucleolar-organizing regions are the sites of the gene on chromosomes. The present study was aimed to show the antitumoral effect of curcumin via AgNOR protein synthesis in Ehrlich's ascitic carcinoma (EAC) bearing mice. Twenty three mice with EAC were randomly divided into 3 groups as positive control (n = 7), group 2 (n = 8) and 3 (n = 8) treated intraperitoneally with curcumin (25 mg/kg) and (50 mg/kg), respectively. The animals were sacrificed on Day 16, the solid tumors were removed out. Then, total AgNOR area/nuclear area (TAA/NA) and the mean AgNOR number were estimated for each mice. Statistically significant differences were determined among the whole groups for TAA/NA ratio (p = 0.000), conversely mean AgNOR number (p = 0.361). When comparingthe two groups; while no difference was determined between the control and curcumin (25 mg/kg) groups (p = 0.061), the significant differences were detected between the control and curcumin (50 mg/kg) groups (p = 0.000) and between curcumin (25 mg/kg) and curcumin (50 mg/kg) groups (p = 0.000) for TAA/NA ratio. However, there was no significant difference for the mean AgNOR number in double comparison of the groups. The current study showed that curcumin had a crucial function against cancer development. Also, both AgNOR values might be used as biomarkers for detection of the most reliable therapeutic dose selection of cancer treatment (Tab. 3, Fig. 2, Ref. 27).

Significance of AgNORs and Ki-67 Proliferative Markers in Differential Diagnosis of Thyroid Lesions

We aimed to assess the utility of quantitative analysis of AgNORs and Ki67 labeling index (LI) in the differential diagnosis of different thyroid lesions. This study included: 25 papillary carcinomas, 7 follicular carcinomas, 21 follicular adenomas and 27 nodular goiters. Using a semiautomatic image analysis system, Ag NORs parameters were measured and calculated including: total area of AgNORs, mean Ag NOR number in nuclei, nuclear area, mean area of AgNOR dots per each nucleus, number of central and marginal AgNOR dots, and the relative ratio of total area of AgNOR dots/total area of nucleus. Ki67 immunostaining was performed and the LI was determined. There was a significant difference between groups of thyroid lesions regarding total area of AgNORs, Ag NOR number and number of marginal Ag NOR dots. According to receiver operating characteristic curve, Ag NORs number =2.91 and marginal Ag NORs = 2.67 were useful cut off values above which follicular carcinoma can be diagnosed with 100% sensitivity, 79% specificity, 76% PPV, 100% NPV and 85% diagnostic accuracy for both parameters. Mean Ki67 LI in our study was 14.12 ± 2.29, 61.42 ± 3.77, 34.90 ± 3.49 and 18.60 ± 1.96 for papillary carcinoma, follicular carcinoma, follicular adenoma and nodular goiter respectively. Ki67 LI showed statistically significant difference between follicular carcinoma and follicular adenoma (p = 0.026) and between papillary carcinoma and follicular adenoma (p = 0.007). Quantification of Ag NORs and Ki67 LI could be used as helpful ancillary methods in the differentiation between different thyroid lesions.

Minichromosome maintenance (MCM) and AgNOR proteins expression in desmoid tumours: a tissue microarray analysis.

In the present study, nuclear proliferative proteins: MCM2, MCM5, MCM7, Ki-67 and AgNORs expression was assessed in paraffin sections from sporadic desmoid tumours using a tissue microarray (TMA)-based immuno- and histochemistry, respectively. Nuclear expression of MCM7, where the percentage of positive cells was 0.87% (± 1.64) (range 0-5%), was found in 4/20 (20.0%) cases. In 32/32 (100%) of the examined desmoid cases no expression of nuclear proteins MCM2 and MCM5 was detected. Nuclear expression of Ki-67 was observed in 4/21 (19%) cases. Paraffin sections from 30 cases of desmoid tumours were silver-stained to visualize AgNORs. The following AgNOR parameters were calculated: mean AgNOR number per nucleus (N), mean AgNOR area per nucleus, mean AgNOR dot area per nucleus (A), and mean AgNOR content (C = N/A). In the investigated group the mean values of AgNOR parameters were the following number: 4.34 (± 0.11); area: 0.74 μm2 (± 0.19); dot area: 0.18 m2 (± 0.01), and AgNOR content: 23.73 (± 1.85). The mean AgNOR number per nucleus and mean AgNOR content in desmoid tumours were statistically significantly higher as compared to the controls (tonsil tissue) (p<0.001). This study observed low level of MCM7 and Ki-67 and lack of MCM2, MCM5 proteins expression which may explain commonly known low mitotic activity of desmoid tumour cells. The morphology of dots related to AgNORs (number, area) and their morphometric parameters point to elevated transcriptional activity of desmoid cells.

Evaluation of cell proliferation rate in non-dysplastic leukoplakias

Analyze whether the most frequent cases of non-dysplastic leukoplakias, hyperkeratosis (H), acanthosis (A), and hyperkeratosis with acanthosis (HA) have similar cell proliferation rates and to compare them with epithelial dysplastic (ED) leukoplakias and normal oral epithelium (NOE). The sample comprised 10 cases of normal oral epithelium, 10 cases of hyperkeratosis, 10 cases of acanthosis, 10 cases of hyperkeratosis with acanthosis and 10 cases of epithelial dysplasia. The mean number of AgNORs per nucleus (mAgNOR) and the mean percentage of cells with 1, 2, 3 and 4 or more AgNORs per nucleus (pAgNOR) were recorded. The results of mAgNOR showed differences between disorders in the evaluation of the basal layer, of the parabasal layer, and in the overall evaluation. mAgNOR and pAgNOR=2 increased progressively from normal oral epithelium to hyperkeratosis with acanthosis, hyperkeratosis, acanthosis and epithelial dysplasia (p<0.05). Cell proliferation rate was different between different subtypes of non-dysplastic leukoplakias and this group presented a higher proliferative behavior when compared to normal oral epithelium. It may be suggested that non-dysplastic leukoplakias had different characteristics regarding cell proliferation rates and sometimes showed a proliferative behavior similar to that found in epithelial dysplasia. More studies should be conduced to increase knowledge about the biological profile of non-dysplastic leukoplakias, especially as it pertains to acanthosis.

Assessment of Cytological Atypia, AgNOR and Nuclear Area in Epithelial Cells of Normal Oral Mucosa Exposed to Toombak and Smoking

The purpose of this study was to assess cellular proliferative activity of clinically healthy oral mucosal epithelial cells of toombak dippers and smokers by means of AgNOR counts and nuclear areas via nuclear morphometry. Smears were collected from normal-appearing mouth floor mucosa and tongue of 75 toombak dippers, 75 smokers and 50 non-tobacco users between the ages of 20 and 70 with a mean age of 36 years. AgNORs were counted in the first 50 well-fixed, nucleated squamous cells and nuclear areas were calculated via microscopic stage micrometer. Cytological atypia was ascertained in 6 tobacco users and could not be ascertained in non-tobacco users. Statistically mean AgNOR numbers per nucleus in the non-tobacco users (2.45±0.30) was lower than the toombak dippers (3.081±0.39, p<0.004), and the smokers (2.715±0.39, p<0.02), and mean nuclear areas of epithelial cells of toombak dippers (6.081±0.39, p<0.009) and smokers (5.68±10.08, p<0.01) was also significantly higher than non-smokers (5.39±9.4). The mean number of nuclei having more than 3 AgNORs was 28%, 19% and 7% in toombak dippers, smokers and non-tobacco users, respectively. These findings support the view that toombak dipping and smoking are severe risk factors for oral mucosal proliferative lesions and exfoliative cytology is valid for screening of oral mucosal lesions.

Prognostic significance of DNA cytometry in combination with AgNOR investigation

Conclusion. While most results concerning DNA and nucleolar organizer region (AgNOR) parameters fit with previous studies, the percentage of aneuploidy looks like a promising prognostic parameter. The observed intratumoral heterogeneity could represent a possible source of conflicting and inconsistent results. Objectives. The aims of our study were to determine the prognostic relevance of different DNA and AgNOR parameters in laryngeal squamous cell carcinoma (SCC) and compare these findings with established prognostic factors including tumor stage and grade, as well as the detection of possible intratumoral heterogeneity. Materials and methods. Sections from 62 laryngeal SCCs were analyzed for DNA content, DNA index, S-phase, percentage of aneuploidy, and AgNOR. Of 62 samples, 31 morphologically similar tumor samples were analyzed for the same parameters in three different tumor areas defined as tumor center, invasive tumor margin, and transformation margin between tumor and normal-appearing mucosa. Results. Our study showed that DNA and AgNOR parameters correlated with T stage, lymph node involvement, and histologic grade regardless of tumor areas. Significant correlation was found between mean number of AgNOR per nucleus and percentage of aneuploidy. Clinical stage and percentage of aneuploidy correlated with survival (p<0.02). Heterogeneity DNA study revealed aneuploidy in central portions of 90% of tumors, while in margins aneuploidy was demonstrated in about half of the patients.

Quantification of silver-staining nucleolar organizer region in epithelial cells of tongue of mice after exposure to, or intake of, alcohol

The purpose of the current study was to evaluate the effect of alcohol on the proliferative activity of epithelial cells in the lingual mucosa of mice by means of silver-staining nucleolar organizer region (AgNOR) count and area measurements. Forty-eight CF1 mice were separated into three groups. The test groups were submitted to topical exposure to, or intake of, 40% (volume/volume) ethyl alcohol. Biopsy specimens were collected from the middle third of the dorsal tongue at 0, 6, and 12 months, and samples were stained according to the AgNOR technique. Mean number and mean area of AgNOR per nucleus were calculated for 50 basal layer cells and 50 intermediate layer cells. Increases in mean number and mean area of AgNOR per nucleus in intermediate cells were observed at 12 months in the alcohol intake group ( P < .05). Results showed that intake of 40% alcohol increased epithelial cell proliferation in the dorsal surface of lingual mucosa.

AgNOR values are not helpful in the differential diagnosis of pituitary adenomas

Nucleolar organizer regions (NOR) are chromosomal segments in which ribosomal RNA is encoded. AgNOR technique, which reveals these regions, has rarely been used in the diagnosis and preceding the prognosis of pituitary adenoma. The purpose of this study was to determine and evaluate the correlation of hormonal profile with AgNOR counts, the correlation of recurrence with AgNOR counts, and to determine the consistency between the evaluations of the two independent observers. This study covers 33 patients with pituitary adenoma. The slides were stained with hematoxylin and eosin. Silver colloid method was used for NOR, and immunohistochemistry for hormone expressions. Consistency was significant between the two pathologists (for hormonal profile, the Kappa test was used and P<0.001; for AgNOR count, intra-class correlation coefficient was 0.83). There was no significant correlation between mean AgNOR counts and hormone expressions ( P>0.05), and there was also no correlation between mean AgNOR counts and tumor sizes (P>0.05). While no difference between recurrent and non-recurrent patients was found with respect to mean AgNOR numbers ( P>0.05), nucleolar silver staining in the form of AgNOR clusters was more frequently detected in recurrent cases.

Análise quantitativa das AgNORs no carcinoma adenóide cístico intra-oral através da técnica de dupla marcação PCNA/AgNOR

A analise quantitativa das AgNORs e a imunomarcacao para o PCNA tem sido empregadas de forma independente na avaliacao da proliferacao celular de varios tumores, e, em muitos casos, tem mostrado correlacao positiva. Entretanto poucos trabalhos tem avaliado, em um mesmo corte histologico, a relacao entre PCNA e AgNOR. O objetivo deste trabalho foi otimizar a tecnica de dupla marcacao com a finalidade de se estudar simultaneamente a correlacao entre PCNA e AgNOR no carcinoma adenoide cistico (CAC) de glândulas salivares menores. Foram selecionados 16 casos de CAC classificados de acordo com o subtipo histologico. A analise quantitativa das AgNORs foi feita por meio de analise de imagens. As AgNORs foram contadas em cem nucleos PCNA positivos e em cem nucleos PCNA negativos. O numero medio de AgNOR nos nucleos PCNA positivos foi 2,14 ± 0,77, e, nos nucleos PCNA negativos, 1,97 ± 0,79, entretanto esta diferenca nao se mostrou estatisticamente significante (p = 0,2537). Nosso trabalho nao mostrou correlacao entre o numero de AgNOR e a imunomarcacao para o PCNA em CAC quando estes marcadores foram demonstrados simultaneamente atraves da dupla marcacao. Quanto a tecnica, o uso do microondas melhorou a coloracao da AgNOR, permitindo uma reducao no tempo de incubacao com a solucao de prata e uma melhor individualizacao das AgNORs, o que facilitou os procedimentos de contagem.

The effect of desalivation on 4-nitroquinoline-1-oxide-induced tongue carcinogenesis: a morphometric study of nucleolar organizer regions.

Saliva is an important factor in the oral cavity and could be significant in protecting against carcinogens. In experimental models of carcinogenesis, saliva was shown to have a temporary protective effect against the carcinogens DMBA and 4-nitroquinoline-oxide (4NQO). Silver-stained nucleolar organizer regions (AgNORs) are considered markers for both proliferative capacity and prognosis. The purpose of the present study was to investigate the effect of desalivation on AgNOR parameters in lesions induced by the carcinogen 4NQO in a rat model, in order to trace early nuclear changes. The study group consisted of 120 male Wistar-derived rats. The experimental group (n=56) underwent surgical desalivation; the control group (n=56) underwent a sham operation, and both groups were administered a solution of 0.001% 4NQO in the drinking water. A normal group (n=8) did not receive surgery and drank tap water. Rats were sacrificed at 7, 14, 22, and 28 weeks. Formalin fixed, paraffin embedded sections of the tongue were silver-stained and AgNOR parameters were analyzed using computerized image analysis. In both desalivated and control groups, the nuclear area was significantly higher than the normal. This difference was already evident at 7 weeks. The mean AgNOR area was significantly higher in the desalivated group at week 7 and continued to increase over time. The mean AgNOR number was also significantly higher in the desalivated group at week 7. Differences between the desalivated and control groups diminished with time. These changes in proliferative activity, as expressed by AgNOR parameters, presented earlier changes in comparison to those observed in microscopic examination of the same slides. Results suggest that saliva in the oral cavity can delay malignanttransformation, but continued exposure to the carcinogen overrides this effect. AgNOR stain seems to be sensitive and allows for early identification of intranuclear changes.

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.

Nucleolar Organizer Regions in Differentiated Preneoplastic and Neoplastic Endometrial Lesions

The aim of the study was the quantitative assessment of nucleolar organizer regions (NORs) in the cells of preneoplastic and neoplastic endometrial lesions. Retrospective analysis included tissue material obtained from 87 patients with simple and complex hyperplasia with or without atypia and well-differentiated stage-I endometrial adenocarcinoma. Sections were made from routine paraffin blocks and stained with AgNO₃. The mean number of AgNORs per cell was determined. The results obtained indicate that the evaluation of proliferative activity of cells expressed by AgNOR count can help in the distinction between atypical hyperplasia and well-differentiated adenocarcinoma, and thus can serve as a useful pathological criterion.