Silver colloid staining technique for analysis of glioma malignancy

Correlation between argyrophilic nucleolar organizer region staining and brain tumor classification and grading

Distinctions between benign and malignant tumors are less evident in the central nervous system than in other tissues. Since the level of cell proliferation is an important feature in tumor grading, we applied AgNOR in 50 cases of brain tumors with different grades and histological origins in order to check its efficiency in discriminating between benign and malignant cases. We found significant differences between the means of grade I (1.76) and grade IV (2.46) tumors. No significant differences were observed considering the same grading with distinct histological types or age of patients, reinforcing the efficiency of AgNOR.

Techniques to assess the proliferative potential of brain tumors

Assessment of brain tumor proliferative potential provides important prognostic information that supplements standard histopathologic grading. Many laboratories rely on mitotic figures to quantify the proliferative potential of brain tumors, but this conventional cellular proliferative index is subject to inter-observer variability and not consistently predictive for low-and high-grade tumors. Recent advancements in technology have made it possible to use proliferative indices as a standard supplement in pathology laboratories. Non-invasive tumor tissue measurements of cell proliferation can be performed using- bromodeoxyuridine labeling index (BrdU LI), flow cytometry (FCM), MIB-1 antibody to the Ki-67 antigen (MIB-1), proliferating cell nuclear antigen (PCNA), and argyrophilic nucleolar organizing regions (AgNOR). Each of these assays has been described in the literature with respect to its ability to predict tumor grade or outcome. At the present time MIB-1 and AgNOR are the simplest and most reliable of these techniques. In addition, advances in our understanding of the genetic alterations associated with proliferation promise to provide more specific markers of proliferative potential. Beyond the pathology laboratory, radiographic studies such as positron emission tomography (PET), single photon emission computed tomography (SPECT), and most recently magnetic resonance spectroscopy (MRS) have been used as follow-up measures, assessing response to treatment and tumor recurrence, rather than as predictors of response to treatment. These radiographic tools, however, have the potential to provide an assessment of tumor proliferation without the need for invasive measures. In this article, we present a review of the current techniques utilized to understand the proliferative potential of brain tumors.

Quantitative cytological assessment of Ki67 and AgNORs using computer-digitized image analysis of four clinicopathological breast lesions

Analysis of silver-stained proteins associated with nucleolar organiser regions (AgNORs) is proposed as a marker of cellular proliferation. This study describes the application of AgNORs and Ki67 in breast lesions. Sixty-one cases including fibroadenoma (FA), fibrocystic disease (FCD), ductal carcinoma in situ (DCIS) and invasive carcinoma (IC) were studied by image analysis to evaluate quantitative changes in AgNORs in both Ki67-positive, and Ki67-negative smears. The Ki67 index was assessed. Morphometric features of cell nuclei and AgNORs were determined by digitized computer image analysis (Prodit 5.2). The growth fraction was 5.08 for FA, 5.71 for FCD, 16.75 for DCIS and 23.26 for IC. The mean nuclear area was significantly higher in malignant cells than those of fibroadenoma and fibrocystic disease. In Ki67-positive cells the total area, long axis and number of AgNORs increased progressively across disease groups. Eccentricity of AgNORs and AgNORs: nuclear area ratios were significantly increased in malignant breast lesion in comparison with benign lesion in Ki67 positive cells. In Ki67 negative cells, the highest value of AgNORs was observed in DCIS. The AgNORs: nuclear area ratio demonstrated a statistically significant trend across the disease groups. This study demonstrates that the growth fraction, mean nuclear area and selected AgNORs features have potential for differentiating benign from malignant breast tumours.

Prognostic relevance of AgNORs in tumor pathology

The importance of the analysis of the silver-stained nucleolar organizer regions (AgNORs) for prognostic purposes in tumor pathology has been reviewed. Current available data from the literature demonstrate that the evaluation of the quantity of interphase AgNORs is an independent prognostic factor in several types of human tumors. Results of our investigations indicate that AgNORs are the most powerful variable predicting survival in patients with pharyngeal carcinoma, multiple myeloma, male breast and prostate carcinoma. The combination of AgNOR counts and histologic pattern allows the stratification of patients with multiple myeloma, pharyngeal and prostate carcinoma into low- and high-risk groups, which could benefit from different therapy. Moreover, AgNOR analysis predicts response to treatment in adult patients with acute myelogenous leukemia, and appears as an independent prognostic factor in a prospective study on renal cell carcinoma. Therefore, AgNOR analysis is a really important prognostic factor for several human neoplasias. The experimental and theoretical justifications for AgNORs as a prognostic factor are also reviewed, in particular the strict correlation between AgNOR quantity and tumor cell doubling time. Lastly, the lack of prognostic significance of AgNOR analysis in some circumstances is critically discussed.

Inhibitory effect of antisense epidermal growth factor receptor RNA on the proliferation of rat C6 glioma cells in vitro and in vivo

OBJECT

The goal of this study was to evaluate the effect of antisense epidermal growth factor receptor (EGFR) RNA on the growth of rat glioma cells in vitro and in vivo and to determine the feasibility of targeting the EGFR gene for gene therapy in gliomas.

METHODS

Antisense EGFR complementary (c)DNA was transfected into C6 glioma cells by using lipofectamine. In vitro studies, Southern and Northern blot analyses, in situ hybridization, and immunohistochemical staining were designed to examine the integration and expression of antisense EGFR constructs. The 3'(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and the average number of argyrophilic nuclear organizer regions (Ag-NORs) were used to evaluate cell proliferation, whereas the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) method and microscopy were used to observe cell apoptosis. As part of the in vivo studies, parental C6 cells and C6 cells transfected with EGFR antisense cDNA were implanted stereotactically into the right caudate nucleus of Wistar rats (C6-injected animals and transfected C6-injected animals). Rats with well-established cerebral C6 glioma foci were treated intratumorally with either antisense EGFR cDNA or empty-vector DNA by using lipofectamine (treated-C6 and control treated group). The general behavior and survival of the rats, findings on magnetic resonance images of their brains, histopathological changes, proliferation activity, and apoptosis of the cerebral gliomas in each group of rats were examined. Exogenous antisense EGFR cDNA was integrated into the genome of C6 cells and expressed. In clones with a high expression of the antisense construct, there was a dramatic decrease in endogenous EGFR messenger RNA and protein levels, reduced proliferation activity, and induction of apoptosis in vitro. The mean survival time of rats injected with C6 cells was 17.3 days. The mean survival time of rats injected with C6 cells followed by treatment with empty vector in lipofectamine was 15.4 days. Survival time was significantly prolonged in 100% of the rats injected with antisense-transfected C6 cells and in two thirds of the rats injected with C6 cells followed by antisense EGFR cDNA. Magnetic resonance imaging revealed distinct cerebral tumor foci in C6-injected rats and in control rats of the treated group, but none were found in the rats injected with transfected C6 cells. Furthermore, tumor foci disappeared completely in C6-injected rats treated with antisense EGFR cDNA. The cerebral gliomas of the rats treated by injection of antisense EGFR RNA were characterized by reduced proliferation activity and the induction of apoptosis.

CONCLUSIONS

The results of this study indicate that EGFR plays an important role in the genesis of malignant gliomas. It may, therefore, be an effective target of antisense gene therapy in patients with gliomas.

MDM2 and p53 expression in gliomas: a multivariate survival analysis including proliferation markers and epidermal growth factor receptor

p53 and the murine double minute 2 (MDM2) oncoprotein expression was evaluated in paraffin-embedded tissue from 61 patients with central nervous system gliomas (53 astrocytomas and eight oligodendrogliomas) and related to proliferation-associated markers [i.e. proliferating cell nuclear antigen (PCNA), Ki-67 and nuclear organizer regions (NORs)] and epidermal growth factor receptor (EGFR). We used the monoclonal antibodies PC-10, MIB-1, DO-1, 1B1O and EGFR 113 and the colloid silver nitrate (AgNOR) technique. MDM2 and p53 were co-expressed in 28% of cases. A p53-positive/MDM2-negative phenotype was observed in 15% and a p53-negative/MDM2-positive phenotype in 20% of cases. There was a positive correlation of p53 and MDM2 expression with grade and proliferation indices. Univariate analysis in the group of diffuse astrocytomas showed that older age, high histological grade, high PCNA labelling index (LI) and high AgNOR score were associated with reduced overall survival (P < 0.05). p53 LI, Ki-67 LI, AgNOR score, tumour location and grade influenced disease-free survival (P < 0.05), whereas the only parameters affecting post-relapse survival were histological grade and Ki-67 LI (P < 0.1). Multivariate analysis revealed that age, radiotherapy, PCNA LI and p53 LI were the independent predictors of overall survival. p53 LI, Ki-67 LI, MDM2 LI, EGFR LI, grade and type of therapy were independent predictors of disease-free survival, and grade was the only independent predictor of post-relapse survival. Our results indicate that p53 LI and MDM2 LI, EGFR expression as well as proliferation markers (PCNA and Ki-67) are useful indicators of overall and disease-free survival in diffuse astrocytoma patients.

A combined staining method for argyrophilic nucleolar organizer regions and for glial fibrillary acidic protein in astrocytes of human brain

Different protocols are described for the combined staining method by which argyrophilic nucleolar organizer region sites can be evaluated in human astrocytes that are immunoreactive for glial fibrillary acidic protein. Among the four protocols studied, the following method was superior to others in terms of unambiguous visualization of the regions in glial fibrillary acidic protein-positive astrocytes; the first step was immunostaining for the protein with a blue colour reaction of alkaline phosphatase, followed by sequential colloidal silver staining for the regions. By this double staining method, we have demonstrated that the reactive astrocytes found in white matter around the metastatic lesion of carcinoma and the infarction, contain more argyrophilic nucleolar organizer regions in terms of the count as well as the area than glial fibrillary acidic protein-positive astrocytes present in the white matter of the normal brain. In conclusion, the double staining may provide valuable information on the cellular activity of astroglia when performed on routine formalin-fixed paraffin sections of the human brain.

Invasive meningioma: a tumour with high proliferating and "recurrence" potential

A study was undertaken to investigate the correlation between histological invasiveness and proliferating potential and clinical recurrence in meningioma. In 39 meningiomas, the histological findings at the tumour-brain interface zone were classified into 3 types, consisting of 29 cases of non-invasion (NON). 7 cases of nodular invasion (NOD), and 3 cases of intermingled invasion (INT). Proliferating cell nuclear antigen (PCNA) and argyrophilic nucleolar organizer region (AgNOR) indices were studied. PCNA indices (mean +/- standard error) of NON, NOD. and INT were 1.7 +/- 0.1%, 5.2 +/- 0.5%, and 7.5 +/- 0.7%. respectively, and the AgNOR indices (dot number/nucleus) were 1.50 +/- 0.03, 2.00 +/- 0.04, and 2.22 +/- 0.07, respectively. Significant differences were found among the three types in both parameters. Clinically, tumour recurrence was observed in 1/29 NON, 4/7 NOD, and 2/2 INT cases, indicating a higher incidence of recurrence in invasive meningiomas (NOD plus INT). Four of 32 patients who underwent gross total removal of the tumours showed recurrence, and all of these four tumours were invasive meningiomas. The results of the present study showed that tumour invasiveness as measured by PCNA + AgNOR indices correlated well with high proliferative potential and clinical recurrence.

A correlative study of in vivo and in vitro labeling index using bromodeoxyuridine in human brain tumors

The labeling index (LI) of 216 cases of human brain tumors was determined by the immunohistochemical technique with monoclonal antibody to bromodeoxyuridine (BrdU). The proliferative potential of 110 cases was estimated using the intra-operative intravenous infusion of BrdU at a dose of 200 mg/sq m. In another 106 cases, the in vitro technique of incubating freshly resected tumor tissue fragments with 100 microM bromodeoxyuridine was used. The BrdU LI in these tumors was then correlated with the histological types and the data as determined by both the in vivo and in vitro BrdU incorporation were compared. The results indicate that although in vivo and in vitro techniques could possibly provide equivalent data in some histologic types, a clear statistically valid proof however is not apparent from this study.

Prognostic significance of proliferating cell nuclear antigen (PCNA) expression in gliomas

The relationship between proliferating cell nuclear antigen (PCNA) expression and various clinicopathological indices (age, sex, tumour location, histological type and grade and treatment) and post-operative survival were studied in patients with central nervous system gliomas using univariate and multivariate analysis. The expression of PCNA (PC10 score) was examined immunohistochemically using the monoclonal antibody PC10 on paraffin sections from 45 cases. Univariate analysis showed that a high PC10 score as well as older age, high histological grade and the histological type (astrocytoma) were associated with reduced survival. However, multivariate analysis revealed that only PC10 score and histological type had independent prognostic significance. The most important feature influencing PC10 score was the tumour grade. Regarding the patients who relapsed, the survival from the time of original diagnosis was related to the relapse-free period, while the PC10 score of the primary tumour emerged as the only independent predictor of survival following the first recurrence. These results indicate that PCNA expression is an independent prognostic indicator in CNS gliomas.

Regional differences in bromodeoxyuridine uptake, expression of Ki-67 protein, and nucleolar organizer region counts in glioblastoma multiforme

To investigate intratumoral differences in indices of tumor cell proliferation, we measured the bromodeoxyuridine labeling index (BrdUrd LI), the Ki-67 protein proliferating cell indices (PCIs) determined by monoclonal antibody MIB 1 in microwave-processed paraffin sections (MIB 1 PCI) and in some cases by monoclonal antibody in frozen sections (Ki-67 PCI), and counts of argyrophilic nucleolar organizer regions (AgNORs) in 20 glioblastomas. In the most actively proliferating areas, MIB 1 and Ki-67 PCIs correlated well with the BrdUrd LI and with each other, while AgNOR counts correlated less strongly with these indices. In less active areas, the MIB 1 PCI and BrdUrd LI changed concomitantly from one area to another within a tumor except in areas of pseudopalisading with necrosis; in these areas the BrdUrd LI decreased significantly compared with neighboring tumor tissue, while the MIB 1 PCI did not. There was very little staining of gemistocytic nuclei with either anti-BrdUrd or MIB 1 monoclonal antibodies; this supports the concept that gemistocytes are mainly quiescent cells. AgNORs in all of the above-mentioned areas varied from tumor to tumor, which suggests that they may indicate some cellular activity other than proliferation. The close correlation between the BrdUrd LI and Ki-67 protein PCIs in corresponding regions of glioblastomas suggests that MIB 1 staining of microwave-processed paraffin sections can be used to evaluate the growth potential of individual glioblastomas and possibly of other gliomas as well.

The significance of nucleolar organizer region (AgNOR) score in predicting meningioma recurrence

BACKGROUND

Argyrophilic nucleolar organizer region (AgNOR) has been demonstrated in recent studies of human brain tumors, including meningiomas. The authors used this technique in meningiomas to analyze whether the mean numbers of AgNOR per nucleus (AgNOR score) are related to the recurrence rate or the proliferative potential of meningiomas.

METHODS

AgNOR staining technique was applied to paraffin-embedded sections of 60 meningiomas. Twenty of these specimens also were investigated immunohistochemically with monoclonal antibody (MoAb) against DNA polymerase alpha (Pol.alpha) and with MoAb Ki-67 to compare the AgNOR score with the proliferative potential.

RESULTS

There was a statistically significant difference between the AgNOR score in nonrecurrent meningiomas (2.48 +/- 0.73) and recurrent histologically benign meningiomas after gross total resection (3.20 +/- 0.96) (P < 0.02). The recurrence rate of tumors after gross total resection with an AgNOR score of 3.0 or more was significantly higher than that with an AgNOR score of less than 3.0. The AgNOR score did not always correlate with Pol.alpha or Ki-67 score; the AgNOR score of malignant meningioma that had high proliferative score was not always high.

CONCLUSIONS

This study indicates that AgNOR staining appears to be a simple and useful method for estimating the probability of histologically benign meningioma recurrence even after gross total resection.

A correlation of argyrophilic nucleolar organizer regions with prognoses in patients with maxillary sinus squamous cell carcinoma

Argyrophilic nucleolar organizer regions (AgNORs) were determined by a semiautomatic image analyzer in a group of 28 patients with T2 or T3 maxillary sinus squamous cell carcinoma. The group was separated into recurrent and non-recurrent groups, metastatic and non-metastatic groups, as well as groups strongly or weakly positive for epidermal growth factor receptor (EGFR). The mean number and area of AgNOR dots per nucleus and the mean size of each dot were calculated. The mean number and area were significantly greater than those in normal cells (P < 0.001), but not in recurrent and non-recurrent groups, metastatic and non-metastatic groups and groups separated by EGFR. There was also no difference found in the mean sizes of tumor and normal cells. These results suggest that AgNOR is related to malignant transformation, but not prognosis.

Clinical evaluation of DNA index in human brain tumors

We evaluated the DNA index values in 28 brain-tumor patients showing DNA aneuploidy on the DNA histogram obtained by flow cytometry. In 17 cases among them, the DNA index values were compared to BUdR labeling indices (BUdR-LI). Average DNA indices of individual tumor types were 1.89 +/- 0.10 (6 glioblastomas multiforme), 1.93 +/- 0.05 (4 anaplastic astrocytomas), 1.68 +/- 0.09 (3 malignant meningiomas), 1.24 +/- 0.03 (7 meningiomas), 1.19 +/- 0.05 (2 pituitary adenomas) and 1.86 +/- 0.24 (6 metastatic brain tumors). Slow-growing tumors such as meningioma and pituitary adenoma, had lower values than malignant tumors, except a case of a metastatic brain tumor. All malignant meningiomas had higher DNA index values than the other meningiomas. No difference was observed between the DNA index values of glioblastomas multiforme and anaplastic astrocytomas. DNA index values were correlated with BUdR-LI values (p < 0.05), and seven cases with low DNA index values (1.13-1.31) had low BUdR-LI values of less than 1%. Others with high DNA index values of 1.44 or more had high BUdR-LI values of 3.5% or more. These results suggest that high DNA index values is related to tumor malignancy, and despite the presence of some disparities, many slow-growing brain tumor has low DNA index values.

Myxopapillary ependymoma. Results of nucleolar organizing region staining

BACKGROUND

Although myxopapillary ependymomas are generally benign with a tendency for slow growth and local recurrence, they are capable of spread within the nervous system and of extraneural metastasis. Histologic features have not been helpful in determining which patients are at risk for recurrence or dissemination, making management decisions difficult.

METHODS

A retrospective review was conducted of 14 cases of myxopapillary ependymoma. The nucleolar organizing region (NOR) staining method was used to determine if this technique was useful in the management of these tumors.

RESULTS

Five patients had total resections of encapsulated lesions, four had total resections of adherent tumors, and four had subtotal resections. Twelve received postoperative radiation therapy. With a mean follow-up of 80 months, 12 patients are well and disease-free. Two patients have had recurrences after surgery and irradiation, leading to death in one and disability in the other. The mean number of NOR per cell in eight specimens ranged from 0.4-1.64. The patient who died with intracranial spread had the highest number of NOR per cell.

CONCLUSIONS

Based on these data and a review of the literature, it is recommended that radiation be delayed until recurrence in tumors that have been totally resected. Local radiation therapy may be indicated in subtotally resected tumors. NOR staining shows promise in predicting the likelihood of spread of tumor. Patients with myxopapillary ependymomas should be followed indefinitely because of the potential for late recurrence, even after aggressive therapy.

Proliferative potential of brain tumors. Analyses with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine labeling, and nuclear organizer region counts

Histochemical analyses with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies were done, and argyrophilic nucleolar organizer regions (Ag-NOR) were counted to estimate the proliferative potential of 200 brain tumors. The findings were compared with the bromodeoxyuridine labeling index (BrdU LI), or S-phase fraction. The proliferating cell indexes (PCI), determined by Ki-67 and anti-DNA polymerase alpha monoclonal antibodies were higher and Ag-NOR more numerous in medulloblastomas, glioblastomas, and metastatic carcinomas than in astrocytomas or meningiomas. The Ki-67 and DNA polymerase alpha PCI correlated with the BrdU LI (r = 0.87 and r = 0.84, respectively) and with each other (r = 0.94). The number of Ag-NOR correlated less strongly with these indexes in some tumors. These findings suggest that Ki-67 and anti-DNA polymerase alpha monoclonal antibodies may be useful for estimating the proliferative potential of individual tumors in routine clinical practice. The number of Ag-NOR, however, does not always reflect the growth potential of each tumor.

Argyrophilic nucleolar organizer region counts and prognosis in multiple myeloma

The prognostic significance of argyrophilic nucleolar organizer regions (AgNORs) has been evaluated in bone marrow trephine biopsies from 64 patients with multiple myeloma (MM) prior to therapy. The univariate Kaplan-Meyer survival analysis showed a significant correlation between survivals and AgNOR counts (median of survival 51.3 months for cases with < or = 4.62 AgNORs per plasma cell (PC) versus 16 months for cases with > 4.62 AgNORs per PC; P = 0.0000) or AgNOR distribution in PC nucleus (AgNOR configuration) (median of survival 71.67 months for cases with tightly grouped AgNORs, 16.26 for partially grouped and 11.74 for dispersed AgNORs; P = 0.001). Significant prognostic correlations were also found for monoclonal immunoglobulin type (P = 0.008), platelet counts (P = 0.0078), serum creatinine level (P = 0.0001), Durie's clinical stage (P = 0.02), percentage of plasma cells in bone marrow biopsies (BMPC%) (P = 0.005), pattern of medullary involvement (P = 0.003) and PC atypia (P = 0.009). Borderline result was detected for the percentage of PCs in aspirates (P = 0.06). No significant correlation was found between prognosis and patients age, sex, haemoglobin level, serum albumin or calcium level, marrow cellularity and excess of haemosiderin. Multivariate survival analysis showed that only two variables were significantly correlated with prognosis: AgNOR counts (P = 0.003) and AgNOR configuration (P < 0.001). In addition, the analysis of variance showed significant association between AgNOR number and platelet counts, haemoglobin level, calcaemia, creatininaemia, clinical stage, percentage of PCs in aspirates, BMPC%, pattern of medullary involvement, PC atypia, marrow cellularity and configuration of AgNORs. Our results indicate that AgNOR counts and configuration have prognostic and diagnostic value and therefore they are useful independent parameters to assess the pretherapeutic aggressiveness of multiple myeloma.

Histochemical study of pituitary adenomas with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine labeling, and nucleolar organizer region counts

The growth potential of 65 pituitary adenomas was determined by histochemical analysis with Ki-67 and anti-DNA polymerase alpha monoclonal antibodies, bromodeoxyuridine (BrdUdR) labeling, and counts of argyrophilic nucleolar organizer regions (Ag-NORs). The mean proliferating cell indices (PCIs) determined by Ki-67 and anti-DNA polymerase alpha and the BrdUdR labeling index (LI) were generally very low [1.0 +/- 0.2%, 1.1 +/- 0.2%, and 0.5 +/- 0.1% (+/- SE), respectively]. Apart from adrenocorticotropic hormone-positive adenomas, which had significantly higher indices, there were no statistically significant differences in the indices among the other subtypes of pituitary adenomas. Recurrent tumors had higher Ki-67 and DNA polymerase alpha PCIs and BrdUdR LIs (3.6%, 4.2%, 1.4%) than primary tumors (0.8%, 0.8%, 0.3%; P less than 0.005). The number of Ag-NORs did not correlate significantly with any of the three indices. The mean number of Ag-NORs was higher in nonfunctioning adenomas than in functioning adenomas (2.04 vs 1.66, P less than 0.005); among prolactin-positive adenomas, those treated preoperatively with bromocriptine had more Ag-NORs than untreated tumors (1.75 vs 1.57, P less than 0.005). These results suggest that the Ki-67 and DNA polymerase alpha PCIs and the BrdUdR LI predict the growth potential of individual pituitary adenomas, whereas the number of Ag-NORs appears to correlate with hormone production rather than with the proliferative potential.

Biology and treatment of gliomas

This review discusses some of the recent advances in glioma research and treatment. Our understanding of the characteristics of these tumors has been strengthened by the application of molecular biologic and genetic techniques to pathologic grading and therapy outcome. Newer attempts to correlate imaging modalities to pathologic grading are also discussed. It is anticipated that these developments will strengthen our ability to design improved treatment strategies, an essential goal inasmuch as current treatment schemes have limited benefit. More work needs to be done to understand the biology of these tumors especially the complex interactions of their cytokine expression, multiplicity of genetic abnormalities, and their local environment. Only then will be able to develop improved therapeutic interventions.

Glial fibrillary acidic protein (GFAP) expression and nucleolar organizer regions (NORs) in human gliomas

The frequency of nucleolar organizer regions (NORs) in each glioma tissue and the relation between the expression of glial fibrillary acidic protein (GFAP) and the frequency of NORs was investigated. The number of Ag-NORs per cell for glioblastoma multiforme was significantly higher than that for anaplastic astrocytoma (P less than 0.05) and that for astrocytoma (P less than 0.01). The number of Ag-NORs per cell for GFAP-positive cells was significantly lower than that for GFAP-negative cells in each histopathological grade (P less than 0.01). Moreover, the linear relationship was demonstrated between the Ag-NORs numbers of GFAP-negative cells and bromodeoxyuridine (BUdR) labeling indices. From these results, it is concluded that many GFAP-positive glioma cells may have low growth potential in glioma tissue and GFAP-negative cells may have a close relation to cell proliferation. The combination of immunohistochemical and silver colloid staining is a useful method for investigating the biological characteristics of brain tumors.

Rapid detection of proliferating potential in human brain tumors by nucleolar organizer region staining on squash preparations

Rapid detection of the proliferating potential of 37 human brain tumors was attempted using squash preparations stained by a silver colloid technique for argyrophilic protein associated with nucleolar organizer regions (AgNORs). Less than 1 h was required for staining. The mean number of AgNORs in cell nuclei of malignant or recurrent brain tumors (16 cases) including meningeal sarcoma, recurrent meningioma, recurrent craniopharyngioma, anaplastic astrocytoma, glioblastoma multiforme and metastatic brain tumor was 3.18, and the number for benign brain tumors (21 cases) including meningioma, neurinoma, pituitary adenoma, benign astrocytoma, ependymoma, and adenoma of lachrymal gland was 1.85. The former value was significantly greater than the latter value (P less than 0.001). These results indicate that quantitative analysis of AgNORs in brain neoplastic cells, using squash preparations, is useful to differentiate malignant from benign tumors within 1 h. Thus, this method provides rapid and useful information about the proliferative potential of human brain tumors even during operation.

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.

The standardized assessment of argyrophilic nucleolar organizer regions in meningeal tumors

Tissue markers of cellular proliferation have been recently utilized as prognostic indicators in tumors of the central nervous system. Nucleolar organizer regions represent transcriptionally active sites of ribosomal deoxyribonucleic acid (DNA) and can be identified by a simple argyrophilic technique. The authors describe a standardized approach to the assessment of these argyrophilic nucleolar organizer regions in meningeal tumors. Twenty-five meningiomas were classified histologically into benign, atypical, or malignant groups. In addition, two hemangiopericytomas and one leptomeningeal melanoma were examined. Appropriate sections were silver stained and argyrophilic nucleolar organizer regions were counted in 200 nuclei. The mean argyrophilic nucleolar organizer region count was statistically different (p less than 0.001) between benign tumors (245 +/- 156, 1.23/cell), atypical tumors (497 +/- 135, 2.49/cell), and malignant tumors (921 +/- 59, 4.61/cell). The count for recurrent meningiomas (544 +/- 76) was also statistically different (p less than 0.02) from non-recurrent tumors (329 +/- 183). The standardized assessment of argyrophilic nucleolar organizer regions can be easily performed by any surgical pathology laboratory without specialized equipment and, in meningeal tumors, may be useful as an independent indicator of biological behavior.