Mean Number Of AgNORs Research Articles

Argyrophilic nucleolar organizer region counts in multiple myeloma: a histopathological study on bone marrow trephine biopsies.

Argyrophilic nucleolar organizer region (Ag-NOR) analysis was performed on bone marrow biopsies from 90 patients with multiple myeloma (MM) at presentation. The pattern of AgNOR expression and its relationship to histological features were evaluated. The mean AgNOR number per plasma cell was directly correlated with the degree of MM differentiation (3.18 for G1, 4.36 for G2, 6.13 for G3; P less than 0.0001), with the percentage of bone marrow plasma cells (BMPC%) (3.06 for BMPC% less than or equal to 20, 4.28 for BMPC% 21-50, 5.14 for BMPC% greater than 50; P less than 0.0001), with the pattern of medullary involvement (3.63 for interstitial, 4.44 for nodular, 5.17 for diffuse involvement; P less than 0.001) and with medullary fibrosis (5.23 for cases with fibrosis, 4.29 for cases without fibrosis; P less than 0.05). The plasma cells of G1 MM showed 2-3 large AgNORs, tightly grouped in a central nuclear cluster; those of G2 MM showed a central nuclear cluster composed of 4-5 medium-size dots and/or two clusters of 2-3 dots; the G3 MM plasma cells showed many small dots scattered in the nucleolus or dispersed in the nucleus. Our results indicate the diagnostic value of AgNOR analysis in MM and suggest the use of this method for identifying clones of atypical plasma cells with different proliferative activity in bone marrow biopsies. It allows simultaneous evaluation of the morphology and kinetics of MM cells in routinely fixed, decalcified, paraffin-embedded material.

口腔へん平上皮癌および良性疾患における核小体形成体（Ａｇ‐ＮＯＲｓ）の発現に関する検討

By using a silver staining technique, nucleolar organizer regions associated protein (Ag-NORs) ha ve been studied in paraffin sections of oral squamous cell carcinomas, benign lesions, such as leukoplakia and papilloma, and normal oral mucosa.The mean numbers of Ag-NORs were: squamous cell carcinoma (n=19), 6.18±1.84;papilloma (n=9), 2.70±0.50; leukoplakia (n=10), 2.92±0.69;normal oral mucosa (n=4), 2.48±0.13.There was a significant difference in the mean number of Ag-NORs between squamous cell carcinoma and the other two groups (P>0.05).The number of Ag-NORs seemed to have relations to the cellular atypism of squamous cell carcinoma and the grade of epithelial dysplasia of leukoplakia.These findings suggest that quantification of Ag-NORs may be used for differential diagnosis of malignant and benign oral tumors, and estimation of proliferative activity of oral preneoplastic and neoplastic lesions.

Silver-stained nucleolar organizer proteins in chondrosarcoma

Silver-stained nucleolar proteins (AgNORs) were counted in primary chondrosarcomas of three histologic grades and in metastatic chondrosarcomatous lesions in the lung. The AgNOR numbers of neoplastic cells in primary tumors increased stepwise from grade 1 (4.42 +/- 1.11) through grade 2 (4.94 +/- 1.31) to grade 3 (6.97 +/- 1.10). There was a significant difference in AgNOR numbers between grade 3 and both grades 1 and 2 (p less than 0.001). Furthermore, the mean number of AgNORs in metastatic lesions (9.75 +/- 0.83) was significantly higher than that in primary sites (p less than 0.001). The number of AgNORs therefore reflects the grade of the chondrosarcoma. The results in the present study indicate that silver colloid staining is a useful technique for determining the histologic grade and evaluating the proliferative activity of chondrosarcomas.

Silver-stained nucleolar organizer regions in the normal, hyperplastic and neoplastic endometrium

The numbers of silver-stained nucleolar proteins (AgNORs) were counted in hyperplastic and neoplastic lesions of the endometrium and compared with those of normal proliferative and secretory phase endometrium. In glandular cells in the normal menstrual cycle, the mean number of AgNORs in proliferative phase endometrium (3.8) was significantly higher than that in secretory phase endometrium (2.7, P less than 0.05). The mean number of AgNORs in well-differentiated endometrioid type adenocarcinoma (5.5) was significantly higher than that in both complex hyperplasia without cytological atypia (3.6, P less than 0.01), and simple hyperplasia (3.3, P less than 0.01). Mean AgNOR counts in complex hyperplasia with cytological atypia were greater than those in both complex hyperplasia without cytological atypia (P less than 0.05) and simple hyperplasia (P less than 0.05). Thus, complex hyperplasia with cytological atypia appears to be a direct precursor of well-differentiated endometrioid type adenocarcinoma. These findings suggest that the mean numbers of AgNORs are increased in neoplastic changes in the endometrium, and the one-step colloid method for AgNORs may therefore be a simple and useful technique to examine proliferative activity in neoplastic and pre-neoplastic endometrial cells.

Correlation between nucleolar organizer region score and bromodeoxyuridine labeling index in C6 glioma cell line.

Correlation between the mean number of nucleolar organizer region-associated argyrophilic proteins (AgNORs) per cell and BrdU labeling index (LI), the percentage of S-phase cells, was investigated in vitro using rat C6 glioma cells under several different conditions such as increased concentration of fetal calf serum (FCS) in a stepwise manner in medium. In addition, the effect of dibutyryladenosine cyclic monophosphate (d-cAMP) on the mean number of AgNORs and the BrdU LI was examined. C6 glioma cells cultured with no FCS showed 5.1% BrdU LI and 3.46 AgNOR score. BrdU LI and AgNOR score of the cells cultured with 1% FCS were 26.5% and 6.25, respectively. Those with 5% FCS were 44.7% and 8.41, with 10% FCS; 49.8% and 10.85, and with 20% FCS; 48.4% and 10.64. Treatment of d-cAMP with 10% FCS induced morphological differentiation and reduced BrdU LI (9.4%) and AgNORs score (4.90), compared with C6 cells cultured in medium containing 10% FCS without d-cAMP. Thus, the BrdU LI and AgNOR score of the C6 cells cultured under several different concentration of FCS were shown to be well linearly related (r = 0.97) and both values were decreased with morphological alteration of C6 glioma cells in the presence of 1 mM d-cAMP.

Nucleolar Organizer Regions in Malignant Melanoma and Melanocytic Nevi

Using a silver staining technique, we studied nucleolar organizer regions (AgNOR) in paraffin sections of junctional nevi, compound nevi, intradermal nevi, blue nevi, dysplastic nevi, Spitz nevi, lentigo maligna, malignant melanomas in nevus, superficial spreading melanomas, and nodular melanomas. Two methods of counting black dots within nuclei were employed. One method was to count the discrete black dots within the nuclei, including the tiny black dots seen within the nucleolus; the second method did not take into account the subsidiary cluster of tiny black dots seen within the nucleolus, instead treating these dots as a single structure. Whichever method we used, a significant difference was found between the pooled mean AgNOR numbers for benign and malignant lesions. We found an overlap, however, between benign, in particular Spitz and dysplastic nevi, and malignant lesions when considering individual counts of AgNOR using both methods. We conclude that studying AgNOR does not seem to be a useful technique to differentiate Spitz and dysplastic nevi from malignant melanomas.

Nucleolar organizer regions in various human brain tumors

Nucleolar organizer regions (NOR's) are loops of deoxyribonucleic acid (DNA) which transcribe to ribosomal ribonucleic acid (RNA) by RNA polymerase I. They possess vital significance in the ultimate synthesis of cellular proteins. A silver colloid staining technique for demonstration of NOR-associated proteins (Ag-NOR's) was applied to paraffin-embedded sections from 128 varied brain tumors and to chromosomal preparations from cultured brain-tumor cells. There was a statistically significant difference in the mean number of Ag-NOR's per nucleus between low-grade tumors (1.98/nucleus) and high-grade tumors (2.95/nucleus). It is suggested that the mean number of Ag-NOR's may represent the proliferative potential of brain tumors. Furthermore, high-grade tumors usually showed relatively large Ag-NOR's in a scattered distribution. In chromosomal preparations, the cultured cells displayed five to 12 Ag-NOR's on acrocentric chromosomes. Five of eight cell lines examined demonstrated ectopic Ag-NOR's. This simple staining technique can be easily applied to routinely processed paraffin-embedded sections and will become a useful tool for quick estimation of the proliferative potential of human brain tumors.

Cell proliferation in intracranial tumours: selective silver staining of nucleolar organizer regions (AgNORs). Application to surgical and experimental neuro‐oncology

A novel tool in diagnostic and experimental pathology, the AgNOR-technique, which consists of visualization of ribosomal gene activity by selective silver staining, was applied to 144 cytological specimens of human tumours of the nervous system. The number of silver-stained nucleolar organizer regions (AgNORs) was correlated with the biological behaviour of the tumours investigated; low AgNOR number were observed in benign neoplasms such as meningiomas and schwannomas and higher AgNOR numbers in glioblastomas and metastases. The mean AgNOR number per cell was 3.15 in astrocytomas, 4.5 in anaplastic astrocytomas and 5.86 in glioblastoma multiforme. Benign and malignant lesions showed different distribution patterns of AgNORs, with few but centrally located AgNORs in benign, and multiple but scattered AgNORs in malignant tumours. AgNOR number per cell and AgNOR area revealed an inverse relationship (correlation coefficient -0.15, linear regression). In addition to the human tumours, two N-nitroso-N-ethyl-urea (NEU) induced tumors in BD-IX rats a mixed glioma (G-XIII) and a malignant schwannoma (N-XII), were investigated. Twelve G-XIII gliomas revealed homogenous AgNOR-counts (standard error of the mean less than 10%), with absolute values between the values obtained for human glioblastomas and metastases. Seven N-XIII subcutaneously transplanted schwannomas revealed higher AgNOR values than human schwannomas, but lower than experimental gliomas. It is concluded that the AgNOR method, as a technique for visualization of ribosomal gene activity, is valuable for assessing proliferative activity and malignancy in both diagnostic and experimental neuropathology.

A critical evaluation of AgNOR counting in benign naevi and malignant melanoma

There is considerable variation in the quoted mean numbers of AgNORS per nucleus for benign melanonaevi and malignant melanomas. This is partly attributable to different approaches to AgNOR counting. This study summarizes our experience in devising an optimal technique for counting AgNORs. We show that it is essential to count intra-nucleolar AgNORs in addition to those lying outside the nucleolus to obtain clear separation of naevi from melanoma. Although this seems an onerous task, we further demonstrate that a maximum of only 30 nuclei need to be counted to obtain a mean AgNOR count per nucleus which is representative of the whole lesion. This compares with the arbitrary figure of 100 nuclei chosen by most workers. Only by optimizing and standardizing all aspects of the AgNOR technique including fixation, staining, and counting will mean AgNOR counts per nucleus become a useful quick, reproducible method which can be applied to lesions which pose diagnostic problems such as borderline melanocytic lesions.

Nucleolar organizer regions in glioma

Nucleolar organizer regions (NOR) are loops of ribosomal DNA(rDNA) which are transcribed by RNA polymerase I. They produce ultimately ribosome and protein. Thus they are believed to reflect nuclear activity. We applied silver colloid staining technique to human glioma to examine relationship between the mean number of Ag-NOR and histopathological grading. The mean number of Ag-NOR( S.E of the mean)were in normal brain, in astrocytoma, in malignant astrocytoma, and in glioblastoma multiforme. And there was a statistically significant difference among these. The results show that Ag-NOR technique is a rather simple and rapid method and will become a helpful tool for estimation of the proliferative potential of glioma.

Silver-Stained Structures in Prostatic Carcinoma: Evaluation of Diagnostic and Prognostic Relevance by Automated Image Analysis

The comparison of the diagnostic and prognostic significance of histology, immunohistochemical parameters (PSA, PSP), and silver-stained nucleolar organizer regions (AgNORs) was estimated in paraffin sections taken of 63 prostatic carcinomas prior to therapy. AgNORs were visualized with a one-step silver staining technique with the appropiate staining time determined by preliminary staining-time series. The mean AgNOR number per cell (n) and the mean AgNOR area per silver-stained dot (A) were determined by means of an automatic image analysis system. Thereby prostatic carcinomas exhibited multiple small AgNORs within their nuclei (n = 4.7, A = 0.09 micron 2), whereas benign prostatic epithelium showed few but large silver-stained particles (n = 1.8, A = 0.27 micron 2; p less than 0.001). This relationship was then calculated as a quotient of AgNOR number and area (NQ = n/A) which provided additional information for the diagnosis of malignancy as well as survival. Univariate survival analysis disclosed a set of four variables predicting death from prostatic cancer; cribriform growth pattern, AgNOR quotient, histological grade, and PSA immunoreactivity. Of these parameters, immunoreactivity of PSA failed to prove its prognostic significance in multivariate survival analysis (Cox model). No relation to prognosis was found for the number as well as the area of AgNORs alone. Therefore, image analysis proved to be a prerequisit for the feasibility of this promising technique by providing objective and reproducible results.

Silver colloid staining technique for analysis of glioma malignancy

A silver colloid staining technique for identifying nucleolar organizer region-associated proteins (Ag-NOR's) was applied to 51 human gliomas. These comprised 20 glioblastomas multiforme, 15 anaplastic astrocytomas, and 16 astrocytomas, in which the mean numbers of Ag-NOR's per cell (+/- standard error of the mean) were 2.51 +/- 0.12, 2.01 +/- 0.10, and 1.76 +/- 0.06, respectively. Significant differences among these were recognized, and the mean number of Ag-NOR's paralleled the degree of histopathological malignancy. In 16 cases, studies were performed of the number of Ag-NOR's and the S-phase fraction by in vitro labeling using antibromodeoxyuridine monoclonal antibody. A linear relationship was demonstrated between these two factors (r = 0.857, p less than 0.001), although some scatter was seen. In 32 adult patients, the correlation between the number of Ag-NOR's and the prognosis was estimated. The results demonstrated that the group containing patients with less than 1.80 Ag-NOR's per cell had a better prognosis than the group with 1.80 Ag-NOR's or more. Thus, the number of Ag-NOR's reflected the degree of histopathological malignancy, S-phase fraction, and prognosis. Silver colloid staining for Ag-NOR's is a simple, rapid, and reproducible method for estimating the proliferative potential of human gliomas without requiring a complicated technique.

Prognostic Significance of Nucleolar Organizing Regions (NORs) in Carcinomas of the Sigmoid Colon and Rectum

The prognostic significance of silver-binding nucleolar organizing regions (AgNORs) has been evaluated in tissue sections of biopsies taken from 70 primary adenocarcinomas of the colon sigmoid (n = 25) and rectum (n = 45) prior to their curative resection. A significant correlation between five-year survival rate and the mean AgNOR number per tumour cell (p less than 0.001) and the mean size of silver stained dots (p less than 0.05) was found according to the univariate Kaplan-Meier survival analysis. There was no significant relationship between AgNOR content and grade of malignancy, pT categories or pN categories. Multivariate survival analysis of covariates (Cox regression model) revealed a set of five variables that significantly influenced the patients' outcome: pN categories, AgNOR content, pT categories, maximum grade of malignancy and number of inflammatory cells. From the clinical and pathological parameters studied, pN and pT categories as well as the mean AgNOR number were the most important variables predicting death from colorectal carcinoma. Since the analysis of AgNORs can be performed on routinely processed paraffin-embedded tissue, this method may be of potential use in pretherapeutic assessment of the biologic aggressiveness of the disease.

Relationship between intraepithelial neoplasia of the cervix and the size and number of nucleolar organizer regions

A silver colloid technique was applied to 18 colposcopic biopsies of the cervix. These comprised 7 cases of cervical intraepithelial neoplasia I (CIN I), 5 cases of CIN II, and 6 cases of CIN III. The nucleolar organizer regions subsequently visualized (AgNORs) were enumerated using an oil immersion lens. The maximum diameters of the AgNORs and aggregates thereof were measured, by hand, from carefully calibrated monochrome photographs. The mean numbers of AgNORs subsequently identified steadily increased, whereas the mean sizes of AgNORs decreased from CIN I to CIN III. In CIN I the mean AgNOR number was 2.3 (range 1.8–3.4) and the AgNOR mean maximum diameter ( D max) was 1.28 μm (range 0.75–1.75). In CIN II the mean number was 3.5 (range 3.1–4.6) and the AgNOR D max was 0.98 μm (range 0.9–1.18). In CIN III the mean number was 4.7 (range 4.0–6.1) and the D max was 0.62 μm (range 0.51–0.9). CIN III could be distinguished from CIN I and CIN II on the basis of AgNOR sizes, and an inverse relationship between AgNOR numbers and sizes was established.

Nucleolar organizer regions in rat urinary bladder tumors induced by N-butyl-N-(4-hydroxybutyl)nitrosamine

The number of nucleolar organizer regions (NORs) stained by the one-step silver colloid method was measured in preneoplastic and neoplastic bladder lesions induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in rats. Male ACI/N rats, 6 weeks of age, were given 0.05% BBN in drinking water for 5, 8, 12, 18 and 30 weeks to induce preneoplastic and neoplastic transitional cell lesions. The mean numbers of silver-stained NORs (AgNORs) in such lesions were as follows: untreated transitional epithelium (n = 6), 1.26 +/- 0.09; transitional cell epithelium outside focal lesions (n = 10), 1.75 +/- 0.10; simple hyperplasia (n = 10), 2.01 +/- 0.15; papillary or nodular (PN) hyperplasia (n = 10), 2.15 +/- 0.19; transitional cell papilloma (n = 5), 2.37 +/- 0.12; transitional cell carcinoma (n = 5), 3.52 +/- 0.23. Thus, the mean number of AgNORs showed a step-wise increase from untreated and treated, histologically normal transitional epithelium through simple hyperplasia and PN hyperplasia to transitional cell papilloma and carcinoma. These results suggest that the mean number of AgNORs may reflect the proliferative nature of bladder lesions induced by BBN, as reported in preneoplastic and neoplastic lesions in other organs. PN hyperplasias were classified into two types based upon the mean number of AgNORs, indicating that they include reversible and irreversible changes in contrast with simple hyperplasia which is reversible change.

AgNOR numbers in rat pituitary corticotrophs following adrenalectomy or corticotrophin releasing factor administration

Using a combined silver staining/immunoalkaline phosphatase technique, nucleolar organiser regions (AgNORs) were visualised and quantified in rat anterior and intermediate lobe pituitary corticotrophs following bilateral adrenalectomy or sham surgery. Compared to sham operated animals, the mean number of AgNORs was increased in anterior lobe corticotrophs in adrenalectomized rats and there was a shift to the right in the distribution. At 2 weeks after adrenalectomy, AgNOR numbers were greater than at 6 weeks. AgNOR numbers were also quantified in anterior lobe corticotrophs of intact rats receiving daily intraperitoneal injections of ovine CRF-41 at 50 micrograms/kg, which has been shown to stimulate ACTH release and to produce morphological evidence of increased corticotroph stimulation. CRF-41 did not produce an increase in AgNOR numbers, compared to saline injected controls.

Effects of age, sex and multiple endocrine neoplasia type-II on silver stained nucleolar organizer regions

Silver stained nucleolar organizer regions (AgNORs) were studied in phytohemagglutinin (PHA)-stimulated lymphocytes from 55 Caucasian control individuals (34 females with average age of 24 years and age range 19 weeks gestation to 87 years; 21 males with average age of 31 years and age range 29 weeks gestation to 72 years) and 13 individuals (7 females, 6 males; average age 38.8 years with age range 25–58 years) with multiple endocrine neoplasia-type II (MEN-II), an autosomal dominant malignancy with increased chromosome breakage. For the first time, AgNORs were examined in lymphocytes from normal fetuses and patients with MEN-II in order to determine the effects of age, sex or malignancy on the number of AgNORs. No significant difference in the average number of AgNORs were found in fetal cells (8.2 ± S. D. 0.7/ cell) when compared with cells from older individuals including those over 65 years of age (8.0 ± S. D. 0.8/ cell). There was a statistically significant negative correlation ( P < 0.05) between the modal number of AgNORs on G but not D chromosomes in both males and females. A negative correlation was also found between the mean number of AgNORs and age but was not statistically significant. The average number of AgNORs in the MEN-II individuals was 8.5 ± S. D. 0.7/ cell, which was not significantly different than 8.2 ± S. D.0.7/ cell observed in age-matched control subjects.

Frequency of Ag-stained nucleolus organizer regions in the chromosomes of cattle

Sequential Ag NOR/G-band studies were performed on the chromosomes of 33 Austrian Al bulls. The mean number of Ag-NORs per bull karyotype was 6.06. The distribution of Ag-NORs was found to be characteristic for each individual.