[The significance of blood group-related antigen A in a pancreatic cell line (PGHAM-1) in hamsters. With special reference to cell proliferation]

The relationship between blood group-related antigen A and cell proliferation was studied in a pancreatic carcinoma cell line (PGHAM-1) induced by N-nitrosobis (2-oxopropyl) amine (BOP) in hamsters. In vitro, the cell proliferation of PGHAM-1 was inhibited in a culture medium with an added monoclonal antibody (MoAb) against blood group-related antigen A depending on its concentration. In in vivo experiments, immunohistochemical double staining was performed using MoAb against blood group-related antigen A and bromodeoxyuridine (BrdU) in pancreatic carcinomas by intrapancreatic transplantation of PGHAM-1. Antigen A was expressed in the cell membrane and cytoplasm of PGHAM-1 cells. The BrdU labeling index (LI) in lesions with strong expression of MoAb A (> or = 50%) was 27.4 +/- 5.00, whereas the BrdU LI in lesions with weak expression of MoAb A (< or = 10%) was 11.9 +/- 2.10. The mean LIs in strongly expressed lesions of MoAb A were higher than those in weakly expressed lesions of MoAb A (p < 0.01). These results indicated that antigen A might be associated with cell proliferation in pancreatic carcinomas induced in hamsters.

Anti-BrdUrd labeling of newly synthesized DNA in HL-60 cells triggered to apoptosis

Apoptosis is an active process that takes place during pre- and postnatal life. It can be viewed as the essential counterpart to cell proliferation, both phenomena being aimed at the maintenance of tissue and organ homeostasis. Because apoptosis often takes place during the S phase of the cell cycle, we describe the spatial and temporal correlation between DNA synthesis and DNA cleavage taking place in the same nucleus at the same time as a result of the action of camptothecin on proliferating HL-60 cells in vitro. The relationship between DNA synthesis and DNA fragmentation was studied at the single-cell level by bromodeoxyuridine (BrdUrd) incorporation revealed by flow cytometry, electron microscopy, and confocal microscopy. Most HL-60 cells are triggered to apoptosis during the first hour of treatment with camptothecin, and only cells in early-middle S phase are sensitive to the drug effect, whereas late S phase cells appear insensitive to camptothecin-induced apoptosis. Our data, therefore, reinforce the hypothesis of a DNA strand break threshold that may exist in the cell, beyond which the apoptotic program is activated. Moreover, DNA synthesis activity in the nucleus committed to apoptosis is gradually downregulated; after 6 h of camptothecin treatment, virtually no residual DNA replication activity can be detected in micronuclei. DNA repair does not appear to be involved in bromode-oxyuridine incorporation during the apoptotic process.

Laser scanning cytometer (LSC) analysis of fraction of labelled mitoses (FLM)

In this report we describe the successful application of a novel microscope-based multiparameter laser scanning cytometer (LSC) to measure duration of different phases of cell cycle in HL-60 human leukaemic cell lines by the fraction of labelled mitoses (FLM) method. Exponentially growing cells were harvested after various time intervals following pulse-labelling with 5'-bromo-2'-deoxyuridine (BrdUrd), cytocentrifuged, fixed in ethanol, and then exposed to UV light to induce DNA strand breaks at the sites of incorporated BrdUrd. The 3' OH termini of the photolytically generated DNA strand breaks were labelled with BrdUTP in the reaction catalysed by exogenous terminal deoxynucleotidyl transferase (TdT), followed by FITC-labelled BrdUrd antibodies. DNA was counterstained with propidium iodide (PI). Due to differences in chromatin structure between the interphase and mitotic cells, the LSC identified the latter by virtue of their higher red (PI) fluorescence intensity values among all pixels over the measured cell. To confirm that the cells selected were indeed cells in mitosis, predominantly in metaphase, the recorded X-Y coordinates of selected cells were used to re-position the cell for their visual examination. From the time lapse analysis of percentage BrdUrd-labelled cells progressing through mitosis it was possible to calculate the duration of individual phases of the cell cycle. The duration of S (Ts) and G2 + M (TG2 + M) was 8 and 3 h, respectively, and the minimal duration of G2 (TG2) was 2 h. The cell cycle time (Tc) estimated for the cohort of the most rapidly progressing cells was 13 h. The ability to automatically and rapidly discriminate mitotic cells combined with the possibility of their subsequent identification by image analysis makes LSC the instrument of choice for the FLM analysis.

Immunohistochemical demonstration of S-phase cells by anti-bromodeoxyuridine monoclonal antibody in cattle tissues

Bromodeoxyuridine (BrdU), a non-radioactive thymidine analogue, was administered to 15 cattle at a dosage of 1-10 mg/kg intravenously or intraperitoneally to demonstrate S-phase cells in the tissues. The organs and tissues were fixed in 10% neutral buffered formalin or in 70% ethanol, sectioned, denatured with hydrochloric acid, and treated with monoclonal antibody against BrdU. Immunohistochemical methods were used to "visualize" BrdU-labelled nuclei. BrdU-positive cells were satisfactorily demonstrated in both formalin- and ethanol-fixed tissues of animals given doses of 2 mg/kg or over, by either route of administration. Large numbers of BrdU-positive cells indicative of active cell production were found in the basal region of the stratified squamous epithelium, the neck between gastric pits and gastric glands in the abomasum, and the crypts of Lieberkühn of the small and large intestines. Moderate numbers of positive cells were observed amongst inflammatory cells in cases of nephritis and in granulation tissue. Numerous positive cells were detected in leukaemia cells. The study showed that BrdU can be used to measure proliferative S-phase cells in cattle, as in human beings, mice and rats.

1-(2-Tetrahydrofuryl)-5-fluorouracil in combination with uracil suppresses mammary carcinogenesis and growth of tumors induced with 7,12-dimethylbenz[a]anthracene in rats

The effects of 1-(2-tetrahydrofuryl)-5-fluorouracil in combination with uracil (UFT) on mammary carcinogenesis and growth of tumors induced with 7,12-dimethylbenz[a]anthracene (DMBA) were investigated in rats. Daily oral administration of UFT reduced the incidence and number of mammary tumors compared with those of the DMBA control group, resulting in lower activities in DNA synthesizing enzymes, thymidylate synthetase and thymidine kinase, and a reduction of bromodeoxyuridine-immunoreactive (S-phase) cells in mammary tumors of UFT-treated rats.

Early events of liver regeneration in rats: a multiparametric analysis

5-Bromodeoxyuridine (BrdU), a synthetic analogue of thymidine, has been utilized in vivo to detect the proliferation which occurs in the liver after two-thirds surgical hepatectomy. Immunocytochemical detection of BrdU incorporation has been carried out at both the morphological and flow cytometrical level, while structural changes of regenerating liver have been investigated, using Mallory-Azan-stained paraffin sections, by means of an image analyser. The results obtained show that in vivo DNA synthesis progression throughout S phase follows a pattern similar to that previously described in vitro in both 3T3 fibroblasts and Friend erythroleukemia cells and also demonstrate a precise correlation between morphological patterns of BrdU incorporating cells and their lobular distribution. Moreover, the activation of at least two proliferation waves can be detected from 18 to 34 h after hepatectomy: the former, starting from adjacent regions of contiguous lobules, apparently induces an irregular increase of lobular dimension; the latter, involving both inner and peripheral lobular domains, seems to be correlated with the appearance of nodule-like structures at the lobule periphery. In view of these results the role of the hepatic acinus and the hypothesis of a streaming of parenchymal cells during liver regeneration have been discussed.

Bromodeoxyuridine and iododeoxyuridine double immunostaining for epoxy resin sections

To establish bromodeoxyuridine (BrdUrd)/iododeoxyuridine (IdUrd) double immunostaining for thick sections of epoxy resin-embedded tissues, young hamsters received intra-peritoneal injections of IdUrd and BrdUrd 3 hr and 1 hr before sacrifice, respectively. The intestines were fixed with phosphate-buffered 4% paraformaldehyde and embedded in an Epon-Araldite mixture. The epoxy resin was removed completely by a sodium methoxide/benzene/methanol solution. This epoxy resin removal method was effective for BrdUrd/IdUrd immunostaining using a mono-specific antibody for BrdUrd (Br-3) and a bi-specific antibody for BrdUrd (Br-3) and a bi-specific antibody for BrdUrd and IdUrd (IU-4), followed by the ABC complex method. Epoxy sections stained with these antibodies showed clear localization of nuclei incorporating the two thymidine analogues with precise morphology of labeled cells. Furthermore, ultrastructural observation of thin sections adjacent to thick sections immunostained for BrdUrd/IdUrd confirmed the cell type and ultrastructural features of cells labeled with these thymidine analogues.

Plasma cell proliferation in monoclonal gammopathies: measurement using BU-1 antibody in flow cytometry and microscopy: comparison with serum thymidine kinase

AIMS

The labelling index as defined by the percentage of bone marrow plasma cells doubling their DNA in the S phase is a useful prognostic factor in multiple myeloma. The aim of this study was to examine the specificity and sensitivity of a new flow cytometric method for measuring the labelling index.

METHODS

Bone marrow specimens from five patients with monoclonal gammopathy of undetermined significance and 61 patients with multiple myeloma were investigated. The labelling index (LI%) was determined by means of a microscopic and flow cytometric method using the antibromodeoxyuridine antibody BU-1. Serum thymidine kinase, another index of proliferation, was measured by radioimmunoassay.

RESULTS

Good comparability (r = 0.83) and nearly equal imprecision (CV < 20%) were found with microscopic and flow cytometric methods of LI% measurement. However, 1000 or more cells had to be counted by microscopy around the cutoff value to avoid an unacceptable imprecision. Plasma cells with increased S phase (LI% > 1%) were characterised by their reduced light chain fluorescence intensity ratio between plasma cells and nonspecifically stained cells (7.9 v 14.8, p < 0.002), that is, by their generally lowered cytoplasmic immunoglobulin content. There was a moderate correlation between thymidine kinase and labelling index (r = 0.56, p < 0.001). At 100% specificity, myelomas with proliferating plasma cells were more sensitively detected by the labelling index than by serum thymidine kinase (55% v 32% sensitivity).

CONCLUSIONS

The labelling index represents a more specific and sensitive proliferation marker than serum thymidine kinase. Flow cytometry does not result in greater precision.

Epidermal cell migration and healing of the tympanic membrane: an immunohistochemical study of cell proliferation using bromodeoxyuridine labeling

A monoclonal antibody against bromodeoxyuridine (BrdU) was used to investigate cell proliferation in the tympanic membrane of white rabbits. The BrdU-labeled cells were observed mainly in the epidermis of the annulus, around the malleus handle, and in the anterior and posterior superior quadrants of the normal rabbit tympanic membrane at 2 hours after BrdU injection. At 5 days the localization of the BrdU-labeled cells had changed centrifugally from the malleus handle toward the annulus. This change in the distribution of BrdU-labeled cells suggested that epidermal cell migration is caused by cell proliferation and insertion of newly proliferated epidermal cells at the proliferation center. Immunohistochemical observation of BrdU-labeled cells in the artificially perforated tympanic membrane suggested that the process of healing of the perforation may be as follows. Epidermal cell proliferation in the whole tympanic membrane is accelerated by the perforation stimulus. Then the proliferated epidermal cells migrate to the edge of the perforation. In contrast, proliferation of connective tissue cells and mucosal cells is stimulated only around the perforation, and cooperates with the proliferated epidermal cells to close the perforation.

Dual-channel laser scanning microscopy for the identification and quantification of proliferating skeletal muscle satellite cells following synergist ablation

Proliferating skeletal muscle satellite cells are the source of additional myonuclei which allow skeletal muscle to grow and regenerate. Previously, proliferating satellite cells were identified in situ by techniques which were limited either by tissue processing time or inability to observe complete muscle sections, or by errors made in separating these cells from proliferating nonmyogenic cells. To overcome these problems a new method has been devised for the identification and quantification of proliferating satellite cells in situ by light microscopy. The technique involves dual-channel laser scanning imaging of whole muscle sections for the localisation of both the muscle fibre basal lamina and the cell division marker bromodeoxyuridine. Using this technique satellite cell proliferation was quantified in mouse limb muscle following synergist ablation. Dual-channel laser scanning microscopy allowed precise localisation of proliferating satellite cells in the experimental model and, after 4 d, synergist ablation was shown to have produced significant satellite cell proliferation when compared with contralateral and sham-operated controls.

Helicobacter pylori infection does not increase gastric antrum mucosal cell proliferation

OBJECTIVES

Gastric carcinoma is the world's second most common cancer. Recent studies suggest an association between Helicobacter pylori and gastric carcinoma. The aim of this study was to address the effects of H. pylori infection on gastric antrum mucosal cell proliferation.

METHODS

Forty patients undergoing upper endoscopy for standard indications were included in the study. A rapid urease test was used to determine the presence of H. pylori. Epithelial cell proliferation was determined by immunohistochemical techniques utilizing monoclonal antibody to bromodeoxyuridine.

RESULTS

There were no significant differences in the number of labeled cells and in the proliferation fraction (p > 0.1) when patients with H. pylori were compared with those without, and when those over the age of 50 were compared to those under 50. The presence of ulcers similarly had no effect (p > 0.1).

CONCLUSION

Helicobacter pylori infection does not increase gastric antrum mucosal cell proliferation.

Immunocytochemical detection of active DNA synthesis by in vivo labelling with anti-bromodeoxyuridine antibodies in glomeruli of rats with nephrotoxic serum nephritis

We studied DNA synthesis in rats with nephrotoxic serum nephritis (NTSN), a model of a glomerular disease, using in vivo labelling with 5-bromo-2'-deoxyuridine (BrdUrd). NTSN was induced by intravenous injection of subnephritogenic doses of rabbit anti-rat GBM antiserum into male Sprague-Dawley rats. Each rat received a single injection of the DNA precursor, 3H-thymidine analog (BrdUrd), ten min before the tissues were removed. For immunocytochemical detection of DNA synthesis, semithin sections were prepared at various intervals (4 h up to 84 days) after pulse labelling. Using a monoclonal anti-BrdUrd antibody, BrdUrd-incorporated DNA-synthesizing cells were noted in the proliferative zone of the gastric mucosa at all times. In NTSN, BrdUd incorporated DNA-synthesizing cells were detected in the glomeruli from 4h through 28 days after inoculation, with the peak occurring at days 2 to 4. On those days, up to half of the glomeruli showed BrdUrd-incorporated cells, with 8 cells per glomerulus as a maximum. From days 7 to 28, few glomerular cells incorporated BrdUrd, and none did so after day 28. The majority of the BrdUrd-incorporated cells were endothelial. These results suggest that active DNA synthesis by glomerular endothelial cells occurs during a short period of the heterologous phase in this model, and that the lack of mesangial cell proliferation might explain the self-limiting nature of this model. By using in vivo labelling with BrdUrd, we were also able to easily and accurately detect active DNA synthesis without consideration of the normal cell renewal.(ABSTRACT TRUNCATED AT 250 WORDS)

Choice of fixation and denaturation for the triple labelling of intra-cytoplasmic antigen, bromodeoxyuridine and DNA. Application to bone marrow plasma cells

A triple staining method of intra-cytoplasmic antigen, bromodeoxyuridine (BrdU), and DNA for fluorescence image analysis is described. Several kinds of fixation and DNA denaturation methods were tested to obtain a technique suitable for heterogeneous tissues. The model chosen was the analysis of plasma cells in bone marrow. The fluorochromes used were fluorescein isothiocyanate (FITC) for intra-cytoplasmic antigens (light chain immunoglobulins), aminomethylcoumarin acetic acid (AMCA) for BrdU, and propidium iodide (PI) for DNA. The quality of the staining was analysed according to: (1) cell morphology with a good preservation of the chromatin structure, (2) intensity of light chains and of BrdU labelling, and (3) the quality of DNA staining judged from a DNA histogram. For most of the analysed tissues, fixation with methanol followed by 0.5% paraformaldehyde and denaturation by an NaOH concentration adapted to the tissue gave good results. However, in our model fixation by methanol, followed by methanol/acetic acid and denaturation of DNA by 0.03 N NaOH was the solely satisfactory technique. A good correlation (P < 0.001) was found with the plasma cell BrdU labelling index obtained with our reference immuno-enzymatic technique. Quantification of DNA content showed a satisfactory G1 peak coefficient of variation (CV) in diploid cells and a 4C to 2C ratio equal to 2. With this technique, the nuclear and cytoplasmic structures of both myeloid cells and plasma cells were well preserved, while their sensitivity to DNA denaturation was quite different.

Development of microglia in mouse neopallial cell cultures

Microglia develop in cultures initiated from disaggregated neopallial cells of newborn C3H/HeJ mice when the cultures are subjected to nutritional deprivation for 10 or more days (Hao et al: Int J Dev Neurosci 9:1-14, 1991). In the present experiments, the cultures were pulsed with BrdU for 3 hours at different times during incubation and then the cells were immunoreacted with antibodies against BrdU, GFAP, and CR3 receptor. The dividing cells (BrdU+) were found to be either GFAP+ or GFAP-, but not Mac-1+/BrdU+. Infection of proliferating cells after 2 or more days of incubation with replication-deficient retroviral vector containing E. coli lacZ reporter gene resulted in many labeled astroglia cell clones but no labeled microglia. However, when cells were infected right after disaggregation of neopallium, labeled Mac-1+ microglia were found. When Mac-1+ cells in a suspension of disaggregated neopallial cells were killed using complement mediated lysis before setting up the cultures, Mac-1+ microglia developed, in spite of the treatment. We conclude that in cultures initiated from mouse neopallium there are MAC-1-/GFAP- microglia progenitor cells which do not divide in nutritionally deprived cultures but can transform into Mac-1+ microglia under the influence of astroglia-derived trophic factors. Microglia, which become Mac-1+ (i.e., express CR3 receptor), proliferate extensively in the presence of CSF-1 (which is produced by astroglia).

Immunohistochemical analysis of S-phase cells in normal human and rat liver by PC10 monoclonal antibody

The expression of proliferating cell nuclear antigen (PCNA) was examined in normal human and rat liver fixed in either formaldehyde or methanol, and was compared with the incorporation of bromodeoxyuridine (BrdU) in S-phase cells. Codistribution of PCNA and BrdU was assessed in rat liver by double immunohistochemical staining using PC10 and anti-BrdU monoclonal antibodies to identify labelled nuclei of parenchymal and sinusoidal cells. In formaldehyde-fixed human biopsies (n = 13) PCNA-labelling index (PCNA LI) was 0.43 +/- 0.24% (mean +/- SEM) for hepatocytes and 0.09 +/- 0.03% for sinusoidal cells. A great interspecimen variability was observed and a preferential lobular distribution was not evident. In methanol-fixed human liver (n = 8) the immunostaining was strong. PCNA LI was 0.05 +/- 0.01% for hepatocytes and 0.14 +/- 0.01% for sinusoidal cells. 75% of labelled hepatocytes and 60% of labelled sinusoidal cells were found in acinar zone 1. In formaldehyde-fixed rat liver (n = 10) a weak nuclear staining and a great interspecimen variability were evident. LI was 0.13 +/- 0.07% for hepatocytes and 0.40 +/- 0.21% for sinusoidal cells without preferential acinar distribution. In methanol-fixed rat liver (n = 10), PCNA LI was 0.14 +/- 0.02% for hepatocytes and 0.40 +/- 0.04% for sinusoidal cells. 64% of labelled hepatocytes and 50% of labelled sinusoidal cells were found in zone 1. Only on methanol-fixed material did double immunohistochemistry show an almost complete overlap of BrdU and PCNA labelling. The PCNA LIs and the zonal distribution of labelled nuclei as obtained in methanol-fixed material are in keeping with previous reports using 3H-thymidine (3H-Thy) incorporation, suggesting that PCNA immunostaining represents a valid alternative to 3H-Thy.(ABSTRACT TRUNCATED AT 250 WORDS)

Bromodeoxyuridine incorporation in corneal epithelium: an immunocytochemical study in rats

Here we investigate the kinetics of rat corneal epithelium at both single cell and tissue level by means of a BrdU-anti BrdU method. The results obtained have then been compared with those previously obtained by us in rat vocal cord epithelium. In this way two main aspects of BrdU incorporation can be indicated at both light and electron microscopy level. First, we report evidence of a new incorporation pattern corresponding to middle S phase, which is characterized by labelling distribution at the border between interchromatin and heterochromatin at ultrastructural level. Second, by comparing tissue incorporation in rats treated with BrdU at the beginning of light time and at the beginning of dark time, we show an increase of cell proliferation during the last hours of dark time and the first hours of light time. In this way, we demonstrate a different progression of circadian rhythms in peripheral regions of corneal epithelium in comparison with that previously observed in vocal cord epithelium.

Detection of 6-thioguanine-resistant human peripheral blood lymphocytes using 5-bromodeoxyuridine labeling in combination with immunocytochemical staining

Measurement of frequencies of 6-thioguanine-resistant (TGr) human peripheral lymphocytes may contribute to quantitative genetic risk assessment in occupationally or environmentally exposed human populations. A simple procedure for the detection of TGr human peripheral blood lymphocytes was developed in our laboratory, using whole blood culturing and 5-bromodeoxyuridine (BrdU) labeling in combination with immunocytochemical staining. Modifications of the procedure designed to reduce the false positive effects of spontaneously cycling lymphocytes (phenocopies), and to optimize duration of BrdU labeling and the culturing period, were evaluated. A standard procedure was developed which applied 24 h cold storage of the diluted heparinized blood (1:10, v:v in RPMI 1640 medium) at 4 degrees C to reduce the effect of spontaneously cycling lymphocytes, and whole blood culturing in RPMI 1640 complete medium with stimulation of T lymphocytes using phytohemagglutinin (PHA), selection of TGr lymphocytes by adding TG to a final concentration of 2 x 10(-4) M and, after 24 h of incubation, labeling of TGr lymphocytes with 2.5 x 10(-5) M BrdU during 16 h. Using this standard procedure, frequencies of TGr cells in 45 healthy individuals (aged 21-64) were observed to range from 0.3 to 229.8 x 10(-6), with a mean variant frequency (VF) (+/- SD) of 136 x 10(-6) (+/- 35.8). After exclusion of the one extremely high value of 229.8 x 10(-6), mean VF was 8.7 x 10(-6) (+/- 14.1). A significant inverse correlation was found between logVF and the labeling index of control cultures (LIc), indicating that cultures with low LIc tend to yield higher VF.(ABSTRACT TRUNCATED AT 250 WORDS)

A kinetic study of the glomerular cells of developing and mature rat kidneys using an anti-bromodeoxyuridine monoclonal antibody

Newborn and mature Wistar rats received a single intraperitoneal injection of 5 bromo-2'-deoxyuridine (BrdU), a DNA precursor, to assess cellular proliferation by labeling S-phase cells. For immunohistochemical analysis, paraffin sections were prepared two hours after BrdU injection. The various stages of development of the glomeruli were observed within each newborn rat. The most primitive glomeruli were found close to the renal capsule, with progressively more mature glomeruli appearing in the deep renal cortex. BrdU-positive nuclei were frequently detected in the epithelia of nephrogenic vesicles, S-shaped vesicles and ureteral buds. When the capillaries invaded the S-shaped vesicles, the developing glomerular basement membrane was recognizable. In this and more mature stages of the glomeruli, presumptive podocytes no longer showed BrdU-positive nuclei, but they were easily detected in the mesangial and endothelial cells of the glomerular tufts. The mean labeling index of the glomerular tuft cells of mature rats was approximately 0.54%. The majority of labeled cells in the glomerular tufts were endothelial cells. Mesangial cells had a low labeling index. Podocytes revealed no evidence of proliferation. The labeling index of Bowman's epithelial cells, however, was approximately 0.71%, higher than that of the tuft cells. These findings may contribute to a better understanding of the mechanisms of cellular interplay within the glomeruli.

Detection of 5-bromo-2-deoxyuridine (BrdUrd) incorporation with monoclonal anti-BrdUrd antibody after deoxyribonuclease treatment

We studied the effects of deoxyribonucleases on the detection of 5-bromo-2-deoxyuridine (BrdUrd) by anti-BrdUrd monoclonal antibodies (mAbs). After DNase I treatment, BrdUrd was detected in cells fixed on slides with the anti-BrdUrd mAbs, B44 and BMC9318. The level of detection related to the degree of DNA digestion. DNA digestion of 25-75% resulted in levels of staining comparable to control preparations in which DNA was denatured by heating with formamide. Staining with the mAbs of DNase I-treated cells was abolished with S1 nuclease, a single-stranded DNA-specific nuclease. When exonuclease III was used after DNase I treatment, the staining intensity of cells fixed on slides increased, and BrdUrd could be detected in suspended cells by flow cytometry. Since this enzymatic method leading to the detection of BrdUrd does not involve cell loss, or destruction of either cellular morphology or epitope reactivity, as occurs with traditional DNA denaturation procedures, it is useful for kinetic studies of phenotypically mixed populations. Furthermore, staining with anti-BrdUrd mAb of cells treated with exonuclease III offers a simple approach to quantitation of apoptotic cells, in which an endogenous endonuclease is activated.

Simultaneous demonstration of infecting fungi and DNA-synthesizing epithelial cells in the skin

An excellent staining method to demonstrate in vivo dermatophytes and DNA-synthesizing cells in the skin is described. Deparaffinized sections of guinea pig skin, infected with dermatophytes and given bromodeoxyuridine (BrdU) by intraperitoneal injection, were used. Periodic acid-Schiff (PAS) stain in combination with an immunohistochemical stain using anti-BrdU monoclonal antibody allowed simultaneous visualization of fungi and DNA-synthesizing epithelial cells in the skin. Many epithelial cells near the infecting fungi in follicles and interfollicular skin were labelled with BrdU. Only a few BrdU-positive cells were observed in the skin of uninfected animals.

Regeneration of the intralobular duct and acinus in rat submandibular glands after YAG laser irradiation

The present study was performed to understand the regeneration of the intralobular duct and acinus of partially injured salivary glands. Sections of rat submandibular glands irradiated with YAG laser were investigated histologically, and the proliferative activity of regenerating tissue was also investigated immunohistochemically with anti 5-bromo-2'-deoxyuridine (BrdU) monoclonal antibody. After YAG laser irradiation, duct-like structures continuous to the remaining ducts were regenerated at the periphery of the injured lobule. At the distal end of the duct-like structures, squamous cells were shown to form epithelial clusters. Additionally, immature acinar cells appeared budding off from the duct-like structures. During regeneration, BrdU-positive cells were observed in these duct-like structures, epithelial clusters, and immature acini. This study showed that duct-like structures, epithelial clusters and immature acini appear during the regeneration process of partially injured lobules, and that each structure proliferated in order to contribute to the rapid regeneration of the salivary gland.

Cell-cycle analysis detecting endogenous nuclear antigens: comparison with BrdU-in vivo labeling and an application to lung tumors

The versatility of non-radioactive cell-cycle analysis in detecting endogenous nuclear antigens of the proliferating cells was evaluated. Optimal conditions for immunostaining varied in fixation and pretreatment procedures among antigens, bromodeoxyuridine (BrdU), Ki-67 epitope, DNA polymerase alpha and PCNA. A significant correlation between BrdU labeling index (LI) was observed in each positive ratio (PR, positive/total neoplastic cells) for nuclear antigens in tumor-sections which had been labeled in vivo with BrdU. The best correlation was observed in Ki-67 PR (y = 1.26x + 2.5; y = Ki-67 PR; x = BrdU LI; r = 0.97). To determine its prognostic value, Ki-67 analysis was applied to the surgically resected lung tumors. Ki-67 PR were different according to the histologic types of the tumors: 47.8 +/- 3.4% in small cell carcinoma; 29.5 +/- 3.5% in squamous cell carcinoma; 28.3 +/- 4.7% in large cell carcinoma; 15.2 +/- 1.8% in adenocarcinoma and 0.1 +/- 0.1% in mature carcinoid tumor. When the mean value was used to divide each type to a higher or lower proliferative activity (15% Ki-67 PR for adenocarcinoma and 30% for squamous cell carcinoma), the group with the lower Ki-67 PR showed a significantly more favorable prognosis than that of a higher ratio. Ki-67 PR was not correlated with other pathologic factors such as size, lymph node metastasis or pleural involvement. Non-radioactive cell-cycle analysis was feasible and useful for detecting endogenous nuclear antigens even in the lung tumors, particularly when the analysis was coupled with histologic typing.

The significance of Ki-67, BrdU and OKT9 expression in determination of myelodysplastic syndromes by use of APAAP technique

Monoclonal antibodies (McAb) to Ki-67, BrdU and OKT9 were used in APAAP technique for determining the proliferative cells of 46 myelodysplastic syndromes (MDS) with 16 serving as normal controls. According to Ki-67 positive labelling, the proliferative fractions of bone marrow cells can be divided into low (< 25%), intermediate (25%-35%), and high (> 35%) grades. The labelling positivity of Ki-67, BrdU and OKT9 in MDS was all higher than that of the controls. Furthermore, the positive percentages of these three McAbs were significantly correlated. From the results of our experiment, an increase in proliferative fraction was related to clinical classification, prognosis, and therapy of MDS. On the other hand, the positive percentage of Ki-67 > 40% and BrdU > 30% or ratio of BrdU to Ki-67 > 80% may be considered as parameters for unfavourable prognosis.

PC10 monoclonal antibody to proliferating cell nuclear antigen as probe for cycling cell detection in developing tissues. A combined immunocytochemical and flow cytometric study

Proliferating cell nuclear antigen (PCNA), also referred to as cyclin, is an auxiliary protein to DNA-polymerase delta and a proposed marker of replicating cells. We have investigated the applicability and limitations of PC10 monoclonal antibody to PCNA in a cell kinetics study of developing human and rat tissues by immunocytochemical and flow cytometric techniques. Our data demonstrate that the epitope recognized by PC10 antibody is resistant to wax embedding, but sensitive to aldehyde fixation; conversely, alcoholic fixative solutions preserve the immunoreactivity to PC10. Tissue distribution, DNA content and bromodeoxyuridine uptake confirm that PC10-immunoreactive cells in alcohol-fixed tissues are cycling (G1-, S- and G2-phases traversing) cells. It is concluded that the PC10 antibody can be regarded as a powerful tool to study cell kinetics and differentiation in developing tissues, provided that the tissue processing is adequate.

The use of streptavidin-coated magnetic beads and biotinylated antibodies to investigate induction and repair of DNA damage: analysis of repair patches in specific sequences of uv-irradiated human fibroblasts

A new immunoextraction method using biotinylated antibodies and streptavidin-coated magnetic beads has been developed and applied to study the repair of uv-induced DNA damage in specific DNA sequences. uv-irradiated cells were allowed to carry out DNA repair for various time intervals in the presence of 5-bromodeoxyuridine (BrdU). Purified and restricted DNA was subjected to an immunoextraction method employing an anti-BrdU antibody (alpha Brdu), biotinylated goat antimouse antibodies (G alpha Mbio), and streptavidin-coated polymeric magnetic beads. Separation of BrdU containing DNA was achieved by using a magnetic device. This extraction procedure resulted in two fractions of DNA, i.e., BrdU-containing and non-BrdU-containing DNA. Both fractions were blotted on filters and subsequently hybridized with specific DNA probes to determine the relative amount of defined fragments in the two fractions of DNA. Repair experiments using normal primary human fibroblasts showed no difference in the incorporation of repair label in the active adenosine deaminase gene and the inactive 754 locus during the first 4 h following uv irradiation. After longer repair times the active gene incorporated more repair label than the inactive gene, consistent with the known preferential repair of cyclobutane pyrimidine dimers from active housekeeping genes.

Cell proliferation of breast cancer evaluated by anti-BrdU and anti-Ki-67 antibodies: its prognostic value on short-term recurrences

The prognostic value of breast cancer proliferative activity was evaluated in 385 women operated for primary, non-metastasised mammary carcinoma. Cell kinetics was measured using two immunohistochemical techniques. Cells in S-phase of cell cycle were labelled in vitro by incubation of fresh tissue fragments with 5-bromo 2-deoxyuridine (BrdU), a thymidine analogue. Nuclei of cells in active DNA synthesis were stained by an anti-BrdU monoclonal antibody (Mab). Cells in interphase and mitosis were detected with Ki-67, a Mab that is known to react with a nuclear antigen present in G1/S/G2/M phases of cell cycle, but not in resting cells. This reagent provides a means of evaluating the growth fraction of neoplastic cells. BrdU was incorporated in a proportion of tumour cells ranging from 0.1 to 65.5% (median 6.8%). In the panel of tumours presented in this report the median percentage of Ki-67 positive cells (Ki-67 score) was 9.0% (range 0.1-77%). The relationship between disease-free survival (DFS), BrdU labelling index, Ki-67 score and 13 different clinico-pathological variables was investigated by multivariate analysis, using the Cox proportional hazards model. Axillary node status (P = 0.009) and Ki-67 score (P = 0.038) emerged as independent prognostic factors. Nodal status and tumour growth fraction allowed division of patients into groups at different risk of relapse: tumours with a proliferative index below the median value showed a lower recurrence rate than tumours with a high proliferative activity (P < 0.001). In particular, no relapse occurred in pN0 patients bearing carcinomas with a Ki-67 labelling < 9.0% 4 years after surgery. These findings suggest that the evaluation of proliferative activity in breast cancer enhances the probability of correctly predicting outcome after surgery and could be of assistance in the planning of adjuvant therapies.

[Clinical study on the cell kinetics of gastric cancer using bromodeoxyuridine labeling index--its relations with DNA ploidy pattern and epidermal growth factor]

Forty fresh gastric cancer specimens were examined by immunohistological staining using anti-BrdU monoclonal antibody, and simultaneously the specimens were studied by DNA ploidy pattern, EGF with flowcytometer and the immunohistological staining. For EGF study, the same 40 gastric cancer formalin fixed specimens were used. The results of flowcytometric measurement were divided into diploid and aneuploid patterns. BrdU positive stained cancer cells were observed in growing border area than in the center of tumor, and histologically in P(+), n(+), ps(+), INF gamma, and in scirrhous type, deep spread type and advanced stage. This data suggested that the BrdU labeling index seemed to be related to invasion, proliferation, and metastasis of cancer cells. However the positive rates of EGF were higher in ps(+), deep spread type and BrdU positive type but not in P(+), n(+), and EGF was considered to related to invasion but not to be related to metastasis. Although aneuploid pattern cancer showed high BrdU labeling index in ps(+), diploid pattern didn't indicate such tendency. High BrdU positive rate aneuploid cancer were seemed to grow quickly, advance in short period and own worse character. Further investigation would be necessary.

Thrombin may contribute to the pathophysiology of central nervous system injury

Thrombin has multiple functions, including its function as a key enzyme during blood coagulation and other physiologic activities. We studied brain tissue reactions to thrombin that might be present in the central nervous system (CNS) following injury. Thrombin and three different types of controls--buffer, albumin, and plasmin--were individually infused into the rat caudate nucleus by a continuous osmotic mini-pump. Brains were examined by conventional histologic and immunohistologic techniques. Antibodies for bromodeoxyuridine (BrdU), glial fibrillary acidic protein (GFAP), vimentin, and laminin were employed to assess the infiltration of inflammatory cells, proliferation activity of cells, and reaction of astrocytes and mesenchymal cells, respectively. The number of inflammatory cells, number of BrdU-positive cells, area and number of vimentin-positive astrocytes, and the area of GFAP-positive astrocytes were quantitatively analyzed. Thrombin caused infiltration of inflammatory cells, proliferation of mesenchymal cells, induction of angiogenesis, and an increase in vimentin-positive reactive astrocytes. These histologic changes caused by thrombin infusion resembled the inflammation, scar formation, and reactive gliosis in the CNS following injury. These results suggest that thrombin may play an important role in inflammatory responses to CNS injury since thrombin is one of the blood borne factors that may interact with brain tissue after CNS injury. The data further suggest that the therapeutic application of antithrombin agents for CNS injury suppresses inflammation and the excessive gliosis and scar formation, which are barriers to neuronal regeneration.

Demonstration of replication patterns on histone-depleted chromosomes

A modified immunologic technique is described for the purpose of demonstrating replication patterns on mammalian chromosomes after partial histone depletion. Replication patterns were induced by BrdU substitution and visualized by BrdU antibodies, coupled with peroxidase (diaminobenzidine/H2O2) or immunogold-detection. The replication patterns obtained by this technique did not reveal any additional details of replication compared to those shown by conventional cytogenetic staining. However, the possibility of demonstrating replication patterns on these partially histone-depleted chromosomes may prove useful for chromosomal in situ hybridization studies since the chromosomes produced are considerably larger than those seen in conventional preparations.

Flow cytometric measurement of RNA synthesis using bromouridine labelling and bromodeoxyuridine antibodies

Nuclear RNA synthesis can be analysed by flow cytometry of cells labelled with 5-bromouridine (BrUrd) and stained with anti-bromodeoxyuridine (BrdUrd) antibody and FITC-conjugated secondary antibody. A panel of 5 different commercially available anti-BrdUrd antibodies was tested on cells of a HL-60 human leukemia cell line, stained as a methanol-fixed nuclear suspension. The BrUrd-induced fluorescence signals were highest with the antibody ABDM (Partec), moderate but reproducible with B-44 (Becton Dickinson), variable or low with BR-3 and IU-4 (Caltag), and not detectable with Bu20a (DAKO). Treatment of BrUrd-labelled nuclei with ribonuclease before staining with antibodies indicated that ABDM and B-44 antibodies specifically recognized BrUrd-substituted RNA, whereas BR-3 and IU-4 antibodies also bound to BrUrd-unlabelled RNA. Combined analysis of BrUrd and DNA contents demonstrated the variation of RNA synthesis during the cell cycle. The BrUrd incorporation was high in the S and G2 phase, variable in G1, and negligible in mitosis. Similar results were obtained using other cell types.

[Application of bromodeoxyuridine (BrdU) and anti-BrdU monoclonal antibody for the analysis of tumor cell kinetics by flow cytometry]

Bromodeoxyuridine (BrdU) is a thymidine analogue which is incorporated into the cells of DNA synthetic phase. BrdU-labeling index (BrdU-LI) of tumor cells can be estimated with an anti-BrdU antibody. Bivariate distributions of BrdU and DNA content are simultaneously obtained by flow cytometric two parameter analysis with a double staining method. The exact DNA synthetic cells are determined using this method by removal of the cells having S phase DNA content without DNA synthesis; quiescent (S0) cells. Once the BrdU-LIs are obtained, DNA synthesis time (Ts) and other time parameters of tumor cell kinetics can be calculated by mathematical methods. BrdU and anti-BrdU monoclonal antibody makes it possible to easily and rapidly recognize the tumor cell kinetics with high accuracy.

[Flow cytometric analysis of proliferative characteristics of human leukemic cells in bone marrows in vivo using bromodeoxyuridine (BrdU) and its monoclonal antibody]

We developed a new method for analyzing the proliferative characteristics of human acute leukemic cells in bone marrows in vivo using BrdU and its monoclonal antibody. The thirty minutes after a bolus BrdU infusion, a 1st bone marrow aspiration (BMP) was performed to calculate BrdU-LI. Then, a 150-minute continuous infusion of BrdU was started. After the infusion, a 2nd BMP was done to calculate the increasing rate of the BrdU-LI for 3 hours. Each of the bone marrow cells was analyzed by FCM. A mean value of 10.4% for BrdU-LI in 22 previously untreated patients was obtained. In 3 of the patients, Ts and Tpot ranged from 13.5 to 33.9 hours and 6.8 to 10.7 days respectively.

[Cell kinetic effect of carcinostatic agents using BrdU and its monoclonal antibody]

We have investigated the cell kinetic effect of four carcinostatic agents (MMC, CDDP, ADR and 5-FU) on the human gastric cancer cell line (KATO-III; signet ring cell carcinoma) by means of flow cytometry (FCM), using bromodeoxyuridine (BrdU) and its monoclonal antibody. Cancer cells in the S phase were first labelled with BrdU and then the bivariate DNA/BrdU distribution was examined to analyze the effect on the cell cycle. Furthermore, cells were reincubated at 24 hours after labelling to evaluate the cell turnover during FCM. MMC, CDDP and ADR assembled the cells into late S phase and G2M phase, while 5-FU assembled them into S phase. after 24 hours, cells with cessation of cell cycle had inhibited their proliferation. We conclude that this technique can be usefully applied as a susceptibility test of carcinostatic agents, since it could define the phase where carcinostatic agents acted on cancer cells.

Bromodeoxyuridine (BrdU) immunocytochemistry by exonuclease III (Exo III) digestion

A new procedure is described to generate single-stranded DNA by exonuclease III (Exo III) digestion for bromodeoxyuridine (BrdU) immunocytochemistry on tissue sections. We compared this procedure with the most widely used procedure of DNA denaturation with 2 N HCl. In vivo and in vitro pulse and continuous labelling of tissues and cells were used. The specimens were fixed in formalin, ethanol, glutaraldehyde, Carnoy's, Bouin's or Zamboni's fixative and embedded in paraffin or used unfixed as cryostat sections or cytospin preparations. After Exo III digestion, BrdU substituted DNA was detected irrespective of the fixation procedure applied. The optimal protocol for nuclease digestion appeared to be simultaneous incubation, of 10 Units Exo III per ml EcoRI buffer and anti-BrdU monoclonal antibody at 37 degrees C. The advantages of Exo III digestion for BrdU immunocytochemistry compared to acid denaturation were: less non-specific nuclear background reactivity, no DNA renaturation, less DNA loss, optimal nuclear morphology, increase in antibody efficiency and the possibility for simultaneous detection of acid-sensitive tissue constituents. Disadvantages of the Exo III digestion are decreased sensitivity and the need for more rigorous pepsin pretreatment. We conclude that Exo III digestion of DNA is an appropriate alternative for acid denaturation for BrdU immunocytochemistry on sections of pulse-labelled specimens.

Growth fraction measured using the comet assay

Growth fraction, an important determinant of tumour response to therapy, was measured using a novel assay in WiDr human colon carcinoma cells grown as monolayers, spheroids, or xenografts. The assay is based on the fact that the anticancer agent etoposide produces DNA strand breaks in proliferating but not non-proliferating cells. Strand breaks were detected in individual cells using the alkaline 'comet' assay, and growth fraction was defined as the fraction of cells containing elevated numbers of DNA strand breaks. The specificity of the method for detecting proliferating cells was verified directly by allowing cells to incorporate bromodeoxyuridine (BrdUrd) into DNA, followed by exposure to etoposide and treatment of the comets with anti-BrdUrd antibodies. All cells stained with anti-BrdUrd antibodies were also damaged by etoposide. Similarly, growth fraction measured using Ki-67 correlated well with the new assay. The accuracy, speed and convenience of the comet assay for measuring growth fraction suggest that it may be useful for predicting response of human cancers to therapy.

An improved method for chromosome banding after fluorescence in situ hybridization: use of a tetramethylrhodhamine-conjugated BrdU antibody

A method for high quality chromosome banding after in situ hybridization with biotinylated probes has been developed. Fluoresceine-conjugated avidin is used for probe detection, while chromosome banding is performed with a tetramethylrodhamine-conjugated anti-BrdU antibody. In this way probe localization and chromosome identification can be performed simultaneously simply by changing the incidental light wavelength.

A quantitative method for evaluating bivariate flow cytometric data obtained using monoclonal antibodies to bromodeoxyuridine

A method is presented for analyzing data from bivariate analysis of cell populations exposed to bromodeoxyuridine and subsequently examined both for the presence of BrdUrd and for the cellular DNA content. It is shown that certain features may be defined in the bivariate data which are constant independent both of cell type and, within limits, experimental variability. These landmark features include the ratio of red, DNA, fluorescence of G2 + M cells to G1 cells, the ratio of green fluorescence corresponding to the non-specific binding of unlabeled G2 + M cells to unlabeled G1 cells, and the distribution of green fluorescence in unlabeled cells. The landmarks make it possible to standardize rules for establishing the separation line between-labeled and unlabeled cells as required in these experiments to obtain estimates of cytokinetic parameters. Values obtained for the DNA synthesis time and the potential doubling time which result from different decision rules for distinguishing labeled from unlabeled are compared in two murine tumor lines. The potential doubling time, but not the DNA synthesis time is shown to depend sensitively on the separation line. Suggestions are presented for analyzing clinical data with this procedure.

Analytical methods for the study of liver cell proliferation

Various cytometric methods for analysis of regenerating rat liver growth (DNA ploidy distributions, binucleation, and DNA synthesis by in vivo BrdUrd incorporation) were evaluated. The overall hepatocellular growth rate (labeling index), the binucleation rate, and separate indices for mononuclear and binuclear cells could be measured simply by microscope counting of collagenase-isolated hepatocytes immunostained for BrdUrd. Flow cytometry of cells stained for BrdUrd and DNA provided labeling indices for the various hepatocellular DNA ploidy classes as well as for nonparenchymal cells (identified by their size-dependent light scatter), but could not distinguish between mononuclear and binuclear hepatocytes. Image cytometry, using fluorescence or Feulgen staining, was inferior to flow cytometry in terms of speed and DNA resolution, but allowed a complete analysis of all hepatocellular DNA ploidy and nuclearity classes. It may therefore be the method of choice, particularly for analysis of liver cell cultures from which single cells are not easily obtained. Fluorescence staining would seem to be preferable to Feulgen staining, since the latter could not be used simultaneously with BrdUrd staining and therefore required a two-step analysis. A non-immunological method, based on the ability of incorporated BrdUrd to quench DNA staining by a Hoechst dye, could only be applied to isolated nuclei, thus giving no information about binucleation. The latter method may be useful for analysis of tumors which are difficult to dissociate to intact whole cells.

BrdUrd incorporation studies for evaluation of spermatogenesis in the blue fox

The utility of BrdUrd incorporation techniques for studies of spermatogenesis was investigated in the blue fox. BrdUrd was injected intraperitoneally followed by collection of testicular tissue by castration/hemicastration at intervals up to 35 days after pulse labelling. Fluorescent tagged monoclonal antibodies against BrdUrd allowed detection of cells with incorporated tracer in histological sections by fluorescent light microscopy as well as in isolated testicular cells by bivariate BrdUrd/DNA flow cytometry. The duration of the spermatogenic cycle was estimated by following the labelled cohort of preleptotene spermatocytes by immunofluorescence in sections through the various stages of maturation to the late spermatid stage. These data were confirmed by bivariate BrdUrd/DNA flow cytometry of testicular cells in suspensions. Furthermore, estimations of the S phase durations and length of the spermatogonial cell cycle were possible. A consistent and satisfactory fluorescence intensity of incorporated label throughout the study shows that degradation of the incorporated label is no practical problem for this type of study, and suggests that the method is an excellent tool for studying aspects of proliferation and maturation during normal as well as perturbed spermatogenesis. Advantages of the described method include avoidance of potential radiation influence on spermatogenesis from commonly used radiolabelled tracers, e.g., 3H-TdR, and that both large and small animals can be investigated at modest cost since the unlabelled BrdUrd is considerably less expensive than labelled tracers.

Investigation of germinative cells in generating and renewed anagen hair apparatus in mice using anti-bromodeoxyuridine monoclonal antibody

To elucidate the cell kinetics in generating and renewed anagen hair apparatus in mice, S-phase cells in dorsal skin of new-born and 14 to 25-day-old mice were labeled with bromodeoxyuridine (BrdU) and stained immunohistochemically using anti-BrdU monoclonal antibody. In primary hair germ, lower and outer cells were positively stained. In hair peg, the positive cells were divided into upper and lower portions. In bulbous hair peg, the lower positive cells gathered at the suprapapillary area, whereas the upper positive cells were located in the outer part of the hair apparatus. The latter positive cells were further divided in the middle and upper parts of the epithelial cord. The upper cells were going to form a sebaceous gland. From the suprapapillary group of germinative cells, hair cortex through the innermost cell layer of the outer root sheath were considered to be produced. The positive cells of the outer middle group may be important for elongation of hair apparatus and produce outer root sheath cells. At the end of anagen phase, first the suprapapillary cells became negative and then the outer root sheath cells became negative. BrdU-positive cells reappeared at the bottom of telogen hair apparatus and formed a secondary hair germ. Then, a similar cell kinetics was repeated in the renewed anagen hair apparatus. The germinative cells were separated into a few groups during the generation and cyclic changes of hair apparatus. Each cell group formed the individual part of the hair apparatus in a coordinate fashion, resulting in dynamic changes of the hair apparatus.

Measurement of cell proliferation by enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody to bromodeoxyuridine

An ELISA was developed and optimized to measure cell proliferation using a monoclonal antibody to bromodeoxyuridine (BrdUrd). Incorporation of BrdUrd into myoblast monolayers, measured as the optical density at 492 nm, increased in response to fetal calf serum, IGF-I and EGF, the ELISA data correlated closely with data obtained by BrdUrd immunocytochemistry (r = 0.984), cell counting (r = 0.972) and tritiated thymidine uptake by liquid scintillation counting (r = 0.990). The BrdUrd ELISA is a useful alternative to measurement of tritiated thymidine uptake by scintillation counting, and has the added advantages of dispensing with the use of radioactivity and of being less labour intensive.

An immunocytochemical method for studying the kinetics of osteoclast nuclei on intact mouse parietal bone

An immunocytochemical method using an antibody against 5-bromo-2'-deoxyuridine has been applied to the study of the kinetics of osteoclast nuclei on intact mouse parietal bones. Osteoclasts containing tartrate-resistant acid phosphatase show nuclei that are positive for the thymidine analogue within 24 hours of injection into four-day old mice. Labelled osteoclast nuclei decline in number with a half-life of 1.3 days, compatible with a random mechanism of cell death rather than a fixed lifespan. This is shorter than has previously been reported and the possible reasons for this are suggested. The main advantages compared with autoradiography are the shortened processing time and the large number of osteoclasts that can be examined per parietal bone.

[Immunohistochemical observation on the proliferative activity of rat liver in early hepatocarcinogenesis]

Anti-BrdU immunoperoxidase staining was used for cytogenetic investigation of altered foci and nodules in rat liver induced by a procedure including intraperitoneal injection of diethylnitrosamine (DEM), feeding of 2-acetoaminoflurene (2-AAF) and 2/3 hepatectomy. Variation in number and size of the altered foci as well as the number of BrdU-positive hepatocytes inside and outside the foci were clearly observed in the early stage of hepatocarcinogenesis. A predominant distribution of BrdU-positive cells was obtained in the peripheral zone of the altered nodules favorable in explaining the phenomenon of monoclonal origin of the altered hepatocytes inside the nodules. This study also indicated that BrdU-immunoperoxidase staining is a reliable and convenient method in studying the dynamic change of DNA-replication in the process of active hepatocellular proliferation.

Simultaneous immunohistochemical detection of IUdR and BrdU infused intravenously to cancer patients

Cell cycle kinetics of solid tumors in the past have been restricted to an in vitro labeling index (LI) measurement. Two thymidine analogues, bromodeoxyuridine (BrdU) and iododeoxyuridine (IUdR), can be used to label S-phase cells in vivo because they can be detected in situ by use of monoclonal antibodies (MAb) against BrdU (Br-3) or IUdR (3D9). Patients with a variety of solid tumors (lymphoma, brain, colon cancers) received sequential intravenous IUdR and BrdU. Tumor tissue removed at the end of infusion was embedded in plastic and treated with MAb Br-3 and 3D9 sequentially, using a modification of a previously described method. Clearly single and double labeled cells were visible, which enabled us to determine the duration of S-phase (Ts) and the total cell cycle time (Tc), in addition to the LI in these tumors. Detailed control experiments using tissue culture cell lines as well as bone marrow cells from leukemic patients are described, including the comparison of this double label technique with our previously described BrdU-tritiated thymidine technique. We conclude that the two methods are comparable and that the IUdR/BrdU method permits rapid and reliable cell cycle measurements in solid tumors.

Cell proliferation in human tumour xenografts: measurement using antibody labelling against bromodeoxyuridine and Ki-67

Cell proliferation was investigated in human tumour xenografts using bromodeoxyuridine (BrdUrd) labelling, evaluated either by flow cytometry or in tissue sections, and also using the proliferation marker Ki-67. BrdUrd labelling was found to increase when cryostat tumour sections were digested with an enzymic solution. This yielded a labelling index up to four times higher than that obtained using the flow cytometer. Ki-67 indices were found to be higher than those reported for human tumour biopsies, as may be expected due to the enhanced growth rate of the xenografts. Significant heterogeneity was observed in the results for cervix, breast and bladder tumours, and the results of the three methods were poorly correlated. However, three of the four tumour types showed that the tumour with the lowest Ki-67 index also had the longest potential doubling time. Since the measurement of Ki-67 index was found technically easier to perform, and also adequately reflects relative tumour cell proliferation, it is preferred over the other techniques.

Determination of 6-thioguanine resistant lymphocytes in human blood by immunohistochemical antibromodeoxyuridine staining

An immunohistochemical method for the determination of 6-thioguanine resistant (TGr) lymphocytes in human blood samples has been developed. The new technique is a modification of the autoradiographic assay and uses labelling of DNA synthesizing cells by bromodeoxyuridine (BrdU) instead of tritiated thymidine. The label is detected immunohistochemically by using a monoclonal antibody against BrdU in single-stranded DNA. Thawed cryopreserved isolated mononuclear cells are cultured with (TG cultures) and without (control cultures) TG for 40 h, the last 16 h with BrdU. The cells are harvested, fixed and put on microscopic slides; for the TG cultures, all material is used, while slides from the control culture are prepared at a dilution of 1:300. The immunohistochemical staining of the slides involves denaturation of DNA in formamide, incubation with anti-BrdU-DNA antibody, followed by a secondary antibody conjugated with peroxidase and staining with diaminobenzidine. Nuclei that have incorporated BrdU appear brown while all other material remains unstained. The number of all labelled nuclei is scored similarly in control and TG slides and the frequency of TGr lymphocytes is obtained by dividing the number of labelled nuclei in TG slides with that (multiplied by the dilution factor) in control slides. The anti-BrdU method will much simplify and speed up the microscopical evaluation of the TG variants and is very suitable for automation.

[S phase cells of regenerative epithelium in the healing process of gastric ulcer determined by an in vitro BrdU-anti BrdU method]

In order to investigate the healing process of gastric ulcer, cell proliferation kinetics of the regenerative mucosa over gastric ulcers was studied by an in vitro bromodeoxyuridine (BrdU)-anti BrdU method. In addition, the effect of histamine H2 receptor antagonists on gastric cell kinetics was also studied. The BrdU labeling index (L.I.) at the site ulcer margin, which were determined by the ratio of labeled cells to epithelial cells of gastric mucosa, were significantly higher in cases of endoscopic A to S1 stage ulcer than in cases of the atrophic gastritis served as control. While the mean L.I. of surrounding mucosa, approximately 1 cm apart from the ulcer margin, in the stage A to S1 were also significantly higher than that of control, the value in the stage S2 was almost comparable to the value of control. There were no differences of L.I. between the cases treated with and without H2 receptor antagonists. These results suggest that in the healing process of ulcer not only reserved epithelial cells at the ulcer margin but also the cells apart from the margin participate in mucosal regeneration. And it seems advisable to consider the stage S2 rather than the stage S1 as the most precise healing stage of ulcer. H2 receptor antagonist may not give an influence on proliferative properties of regenerating mucosal epithelium.

Application of bromodeoxyuridine (BrdU) and anti-BrdU monoclonal antibody for the in vivo analysis of proliferative characteristics of human leukemia cells in bone marrows

To investigate the proliferative characteristics of human bone marrow leukemic cells in vivo, we developed a new method using bromodeoxyuridine (BrdU) and its monoclonal antibody. Thirty minutes after a bolus BrdU infusion, a lst bone marrow aspiration (BMP) was performed to calculate the BrdU labeling index (BrdU-LI). Then, a 150-min continuous infusion of BrdU was started. Immediately after the infusion, a 2nd BMP was done to analyze the increasing rate of the BrdU-LI for 3 h. Each smear was stained by an immunohistochemical method. The BrdU-LI, the duration of S phase (Ts) and the cell cycle time (Tc) of leukemic cells from 13 previously untreated patients with acute leukemias were estimated. A mean value of 7.2% for BrdU-LI was obtained. Furthermore, mean values of 9.7 h and 152.5 h for Ts and Tc respectively were calculated. This method may prove to be useful in the in vivo cell cycle analysis of leukemias and other malignancies.

Replication patterns of the fragile X in heterozygous carriers: analysis by a BrdUrd antibody method

The replication status of the fragile X chromosomes was studied in short-term cultures of lymphocytes from six female heterozygous carriers. The fragile X was induced by adding 0.1 microM fluorodeoxyuridine during the last 24 h of culturing. The replication status of the X chromosomes was studied using a bromodeoxyuridine (BrdUrd) antibody method. BrdUrd was added (1) at a final concentration of 0.2 micrograms/ml during the early S phase of chromosome replication (16-10 h before harvest), (2) at 0.2 microgram/ml during the late S phase (the last 6 h of culturing), (3) at 20 micrograms/ml during the early S phase, and (4) at 20 micrograms/ml during the late S phase. BrdUrd that was incorporated into replicating chromosomes was detected by using a nuclease and BrdUrd monoclonal antibody. The frequency of the fragile X was reduced by BrdUrd treatment. The degree of reduction was more severe in the 20 micrograms/ml than in the 0.2 microgram/ml series and was more severe with late S than with early S treatment. Of the early- and late-replicating fragile X chromosomes, those which were actively replicating during a BrdUrd treatment were more reduced than the others. Thus, the average rate of early and late S treatment with 0.2 microgram BrdUrd/ml was assumed to be the closest reflection of the situation in vivo. There was no correlation between the average rate of the early replicating, active fragile X and the intelligence of the heterozygous carriers studied.