Relationship between magnitude of hypothermia during ischemia and preventive effect against post-ischemic DNA fragmentation in the gerbil hippocampus

Protective effect of hypothermia against DNA fragmentation in hippocampal CA1 field after transient forebrain ischemia in gerbils was evaluated by changing the magnitude of hypothermia. Inhibition of DNA fragmentation was proportional to the magnitude of hypothermia. The result indicates that, in terms of susceptibility to ischemia, hippocampal CA1 neurons are sensitive to a relatively small decrement of temperature, with temperatures </=35 degreesC being critical for the prevention of apoptotic process following transient forebrain ischemia.

Detection of apoptotic cells in cytology specimens: an application of TdT-mediated dUTP-biotin nick end labeling to cell smears

We applied TdT-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling (TUNEL) to cytologic smears in order to detect the cells undergoing apoptosis. These smears were obtained by scraping the cut surface of 9 cases of carcinoma, including renal-cell carcinoma (3 cases), esophageal squamous-cell carcinoma (3 cases), and gastric adenocarcinoma (3 cases), and were fixed and prepared by different methods. The results were also compared with those of tissue sections. TUNEL in smears was generally associated with higher background nuclear stain than in tissue sections. Smears that were fixed in 4% or 8% paraformaldehyde or absolute methanol exhibited results comparable with those of tissue sections, with minimum background in all cases examined. There were no significant differences in TUNEL labeling index among tissue sections and smears fixed in 4% or 8% paraformaldehyde or in absolute methanol. Smears treated in Carnoy's fixative (3:1 methanol:acetic acid) and air-dried smears demonstrated a higher background. TUNEL positivity could not be detected in slides decolorized from May-Grünwald-Giemsa stain. Markedly high background, which may occur as a result of artifactural DNA breaks, was also observed in slides decolorized from Papanicolaou stain, in which TUNEL-positive cells could be evaluated only in 3/8 cases. Application of the TUNEL method to cytology specimens has disadvantages or limitations compared to its application to histological sections, but the method is considered the most suitable one for detecting cells undergoing apoptosis in cytology materials.

Modifications to the in situ TUNEL method for detection of apoptosis in paraffin-embedded tissue sections

The in situ detection of cells undergoing apoptosis is increasingly important in the analysis of injury and degeneration in the central nervous system. Limited information is presently available on the quantification of apoptosis in paraffin-embedded brain tissue sections, a technique which would be most useful in the evaluation of archival tissue for diagnostic and experimental purposes. In this report, optimized conditions for tissue digestion and permeabilization using Proteinase K and Triton X and a quantification method for apoptosis detection are described using brain sections from aluminum maltolate-treated aged and young rabbits as compared to untreated matched controls. This method provides optimal staining of apoptotic cells without the problem of tissue destruction, and should prove useful in evaluating the process of apoptosis in neurodegenerative disorders.

Apoptosis as a prognostic factor in colorectal carcinoma

We investigated the occurrence of apoptotic cell death in 104 colorectal carcinomas by terminal-deoxynucleotidyl-transferase-mediated dUTP-diotin nick end-labeling (TUNEL) to determine whether apoptosis could be a useful prognostic factor. The apoptotic index (AI) was calculated as the percentage of positive cancer cells per 1,000 cancer cells, the median AI being 4.1, with a range of 1.9-4.7. Apoptosis was less frequently observed in tumors with higher malignant potential, such as those at advanced stages Dukes B, C and D, than those at Dukes stage A (P < 0.05); in tumors showing evidence of moderate differentiation than in well-differentiated tumors (P < 0.05); and in tumors with venous invasion or lymph node metastasis than in those without these features (P < 0.05). Moreover, the subgroup of patients with a low AI of < 4.1 had a significantly poorer survival rate than the subgroup with a high AI in tumors at Dukes stage C, the 5-year survival rates being 33% vs 68% (P < 0.05; Cox-Mantel). Our findings suggest that less apoptosis might result in a greater progression of colorectal carcinoma, and that the rate of apoptosis might be an indicator of the degree of malignancy. Thus it would appear that the frequency of apoptosis in tumor cells could be a useful prognostic factor in colorectal carcinoma.

Ticlopidine induced colitis: a histopathological study including apoptosis

AIMS

To describe ticlopidine related microscopic colitis and to assess the occurrence of apoptosis in the colon epithelium.

METHODS

A series of colorectal biopsy samples from nine patients with ticlopidine related chronic diarrhoea were analysed. Biopsies were also taken from five of these patients between two and four months after ticlopidine withdrawal. The number of apoptotic cells in the crypts/mm2 (apoptotic index) was calculated using in situ labelling by terminal deoxyribonucleotidyl transferase (TdT) mediated dUTP-biotin nick end labelling (TUNEL). All specimens were matched to normal colorectal specimens from a control group of comparable age and sex distribution.

RESULTS

Histological examination of the colon biopsy specimens taken from all nine patients with ticlopidine related chronic diarrhoea showed characteristic features of microscopic colitis. The histology returned to normal when ticlopidine was withdrawn. Apoptotic cells were rarely found in controls, and the mean apoptotic index was 0.53. The apoptotic index was significantly higher (16.53) in ticlopidine related colitis, but decreased dramatically to control value when ticlopidine was withdrawn.

CONCLUSION

Microscopic colitis can be induced by ticlopidine and is accompanied by an increase in epithelial apoptosis. Hence, increased apoptosis might be related to drug injury or might be part of microscopic colitis.

Involvement of apoptosis in the rat germ cell degeneration induced by nitrobenzene

Nitrobenezene (NB) produces germ cell degeneration, especially of spermatocytes in rats. To examine the possible involvement of apoptosis in this process, the extent and nature of nuclear DNA fragmentation after NB dosing were assessed using both terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) and DNA gel electrophoresis, in addition to conventional histological and electron microscopic procedures. Adult Sprague Dawley rats were treated with a single oral dose of NB (250 mg/kg) and euthanized subsequently at 6, 12, and 24 h and 2, 3, 5, and 7 days. The earliest morphological signs of germ cell degeneration in testes were found in pachytene spermatocytes 24 h after dosing. Electron micrographs of degenerating spermatocytes showed marked nuclear chromatin condensation at the nuclear periphery and crowding of cytoplasmic constituents, which are characteristic of apoptosis. Coincident with the appearance of such morphological changes, degenerating spermatocytes contained fragmented DNA as revealed by TUNEL. The presence of DNA laddering, a hallmark of apoptosis on gel electrophoresis, was first apparent and most prominent at 24 h, gradually becoming less detectable. No such changes were observed up to 12 h after dosing or in control animals. These results demonstrated unequivocal involvement of apoptosis in the induction of germ cell degeneration caused by NB.

Apoptosis in murine hair follicles during catagen regression

Catagen hair follicle involution has been reported to involve apoptosis, although the precise mechanism has not been satisfactorily resolved. Previous studies have involved solely morphological or electron microscopical methods. We report here studies on murine hair follicles during the first postnatal hair cycle conducted using the terminal deoxy-nucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method. Electrophoresis of DNA isolated from the hair follicles of the same animals was carried out in order to confirm the systematic fragmentation of DNA that typifies apoptosis. On day 10, when all the follicles were growing, there was no evidence of staining with TUNEL in the hair bulbs. Electrophoresis similarly did not show characteristic DNA ladders. By day 15, a few positive cells were observed in the hair bulbs and the numbers had increased by day 17 when many positive cells were seen, especially in the lower portions of the follicles. Electrophoresis demonstrated DNA ladders on days 15, 16 and 17, although the DNA ladder on day 15 was less prominent than that on day 17. These studies confirmed that apoptosis, as identified by techniques that measure DNA fragmentation, occurs in the lower regions of hair follicles towards the end of catagen.

Evaluation of the sensitivity of the terminal deoxynucleotidyl transferase-immunogold technique on Balbani ring genes

Recently, we developed the terminal deoxynucleotidyl transferase (TdT)-immunogold technique for in situ detection of DNA molecules. In this study the potential value and the limitations of the method were evaluated using the giant polytene chromosomes from Chironomus tentans salivary glands. Emphasis was put on the Balbiani rings (BRs), specialized chromosomal sites with exceptionally intense synthesis of large mRNA molecules. Immunolabeling was recorded not only over the bands and interbands of the polytene chromosomes but also over the BR structures. In the BRs, gold particles were present over segments of active transcription units, each with a central chromatin axis and a number of growing RNP products attached to the axis. One third of the transversely sectioned transcription units showed labeling in the central parts, i.e., where the unfolded chromatin axis is located, whereas the growing RNP fibers remained unlabeled. The absence of labeling of the RNP fibers is not likely to be due to lack of accessibility, because anti-RNA antibodies readily decorated the RNP fibers. The nuclear sap and cytoplasm displayed no significant label. These results clearly indicate that the TdT-immunogold technique is specific for DNA and detects not only DNA in compacted chromatin but also fully extended DNA. Its ability to efficiently label a single DNA molecule demonstrates the method's very high sensitivity.

Germ cell apoptosis in rat testis after administration of 1,3-dinitrobenzene

The present study investigated the occurrence of apoptosis in rat testis 6, 12, 24, or 48 h after administration of 1,3-dinitrobenzene (DNB)(25 mg/kg, i.p.). Apoptotic cells were visualized using TUNEL in situ detection. In untreated control animals, occasional tubules contained a few apoptotic nuclei. After DNB treatment, more tubules were apoptotic and more germ cells within individual tubules were affected. The increase in incidence and severity of apoptosis was statistically significant 24 and 48 h after exposure. Spermatocytes were the primary cell population affected. Apoptosis was primarily present in Stages VI-VIII and IX-XIII. DNA ladders, characteristic of apoptosis, were clearly present by 24 h after DNB administration, faint at 12 h, and not present in the control or at 6 h. Although initiating mechanisms may be very different for different chemicals, apoptosis is a common and late manifestation of the testicular response to numerous toxicants.

Flow cytometric apoptosis assays indicate different types of endonuclease activity in haematopoietic cells and suggest a cautionary approach to their quantitative use

Two flow cytometric apoptosis assays, the terminal deoxynucleotidyl transferase (TdT) assay and in situ nick translation (ISNT) assay, were assessed for their ability to quantitate drug-induced apoptosis in CLL lymphocytes. In contrast to HL60 cells, biotinylated dUTP could not be effectively incorporated into apoptotic CLL lymphocytes using exogenous TdT. This suggested that CLL lymphocytes possess a different type of endonuclease that cleaves DNA, leaving blunt or 3' recessed DNA breaks, which are poor substrates for TdT. This possibility was tested using lambda exonuclease, which can convert a blunt or 3' recessed DNA break into a 3' overhang. Apoptotic CLL lymphocytes pre-treated with lambda exonuclease demonstrated increased nucleotide incorporation with TdT. Single-strand DNA breaks are also present in apoptotic CLL lymphocytes, as labelled nucleotides could be incorporated using the in situ nick translation assay. This study suggests that the efficiency of tailing reactions may be limited by the nature of the endonuclease activity in certain cell types and that validation with other parameters is an essential prerequisite to their quantitative use.

Keratocyte apoptosis after corneal surgery

PURPOSE

Programmed cell death (apoptosis) is the controlled death of cells that occurs with minimal collateral damage to surrounding cells or tissue during development, homeostasis, and wound healing. The authors hypothesize the keratocyte apoptosis is an initiating factor in the wound-healing response after refractive surgical procedures. To evaluate the effects of different corneal manipulations, keratocyte apoptosis was examined qualitatively and quantitatively after traditional epithelial scrape-photorefractive keratectomy (PRK), transepithelial PRK, removal of a cap of superficial cornea using a microkeratome, production of a flap of superficial cornea with a microkeratome, and laser-assisted in situ keratomileusis (LASIK) compared with unwounded controls in rabbit corneas.

METHODS

Refractive surgical procedures or their components were performed in rabbit eyes. Keratocyte apoptosis was monitored using the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling assay to detect DNA fragmentation. Cellular morphologic changes were evaluated by electron microscope examination.

RESULTS

Keratocyte apoptosis was noted with each refractive procedure or corneal manipulation and was variable from eye to eye with each procedure. Transepithelial PRK was associated with the lowest levels of central corneal apoptosis, even if the stromal surface was scraped after the procedure. Keratocyte apoptosis is confined to the superficial stroma extending to a depth of approximately 50 microns to 75 microns after epithelial scrape-PRK and transepithelial PRK. Apoptosis was noted in the deeper central corneal keratocytes located anteriorly and posteriorly to the lamellar cut in LASIK.

CONCLUSIONS

There are qualitative and quantitative differences in keratocyte apoptosis between LASIK, epithelial scrape-PRK, and transepithelial PRK. Epithelial injury is an important factor modulating keratocyte apoptosis. The level and distribution of keratocyte apoptosis, along with subsequent repopulation by activated stromal keratocytes, are likely to be important determinants of corneal wound healing associated with variability and regression after PRK and LASIK. Transepithelial PRK induces low levels of keratocyte apoptosis, and, therefore, this approach may be useful for treating higher levels of myopia and for retreatment after regression.

Quantification of apoptotic cells using isolated glomeruli

In order to detect apoptotic cells in the kidney, the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) method is used in tissue sections. But the number of apoptotic cells per glomerulus in several experimental models of nephritides is about 1 per single tissue section even at peak levels. In this study, we have reported that the TUNEL method and immunostaining of cell-specific markers to a whole isolated glomerulus in combination with laser scan microscopy are potentially useful methods for the analysis of cell turnover within glomeruli.

Atm selectively regulates distinct p53-dependent cell-cycle checkpoint and apoptotic pathways

Atm is part of a pathway that responds to DNA damage from ionizing radiation (IR). This pathway involves p53, as Atm-deficient cell lines and mice are defective in p53 induction after IR. p53 is a multi-functional protein that simultaneously regulates distinct downstream pathways controlling cell-cycle progression and apoptosis. However, the mechanisms by which p53 differentially activates downstream pathways are unknown. To determine the relationship between Atm and p53, we examined cell-cycle and apoptotic responses in Atm-, p53-(ref. 8) and p21-deficient mice after IR in the whole animal. As expected, p53 protein levels were not induced by IR in thymus of Atm-deficient mice. IR-induced cell-cycle checkpoint function was also defective, and induction of p21 was attenuated in thymus from Atm-deficient mice. However, IR-induced apoptosis and Bax induction were completely normal; both of which are mediated by p53. IR-induced thymic apoptosis was suppressed in Atm/p53 double-mutant mice but not in Atm/p21 double mutants, demonstrating p53 dependence and Atm independence. Thus, Atm deficiency results in lack of p53 induction by IR, but only selective disruption of p53-dependent functions. Our results support a model in which upstream effectors such as Atm selectively activate p53 to regulate specific downstream pathways, providing a mechanism for controlling distinct cell-cycle and apoptotic responses.

Apoptosis occurs more frequently in intraductal carcinoma than in infiltrating duct carcinoma of human breast cancer and correlates with altered p53 expression: detected by terminal-deoxynucleotidyl-transferase-mediated dUTP-FITC nick end labelling (TUNEL)

AIMS

We examined the relationship between apoptosis and three different major stages of human breast carcinoma: intraductal carcinoma (DCIS), infiltrating duct carcinoma (IDC) and metastatic carcinoma in lymph nodes. We also determined the correlation between apoptosis and oestrogen receptor (ER), progesterone receptor (PR) and p53.

METHODS AND RESULTS

The study investigates the extent of apoptosis in 63 breast carcinomas by in-situ end-labelling, in formalin-fixed, paraffin-processed tissue sections. The 63 breast carcinomas, included 22 DCISs, 26 IDCs, three infiltrating lobular carcinomas (ILC) and 12 metastatic lymph nodes. The apoptotic labelling index was higher in DCIS than IDC and metastatic carcinoma (P < 0.001, P < 0.007, respectively). By immunohistochemistry, we also analysed p53, ER and PR. Apoptosis correlated significantly with p53 (r = 0.748, P = 0.0004) in IDC. Also, ER correlated significantly with PR (r = 0.629, P = 0.00001). No apparent correlation was found between the apoptosis and ER or PR.

CONCLUSION

Our data suggest that not only does apoptosis differ between intraductal carcinoma and infiltrating carcinoma but also it might be regulated by altered p53 expression.

Cadmium-induced apoptosis in the urogenital organs of the male rat and its suppression by chelation

Cadmium-induced apoptosis is shown to occur, in vivo, in several organs of the male Wistar rat urogenital system, 48 h after cadmium administration i.p. at a dose of 0.03 mmol/kg. Characteristic DNA fragmentation (as measured by an enzyme-linked immunosorbent-assay, ELISA) and histopathologically observed changes characteristic of apoptosis are found in the kidney, prostate, seminal vesicles, testes, and epididymis. TUNEL assay also demonstrates the apoptosis. Such changes are absent from bladder and vas deferens tissue. Timely administration of an appropriate chelating agent capable of reaching intracellular cadmium binding sites can suppress the processes leading to apoptosis. Administration of monoisomyl meso-2,3-dimercaptosuccinate (Mi-ADMS, 0.5 mmol/kg i.p.) to cadmium-treated rats is effective in greatly reducing typical histopathologic signs of apoptosis and the associated chromatin DNA fragmentation as revealed by ELISA when the antagonist is administered 1 h after cadmium. Administration of the chelating agent at law times results in greater degradation of DNA into oligonucleotides and more prominent histopathological evidence of apoptotic changes in the affected organs of the rat urogenital system. There is also a progressive increase in apoptotic changes indicated by TUNEL assay, as the antagonist is administered at progressively greater intervals after cadmium.

Apoptotic cell death in rabbit lens after lens extraction

PURPOSE

To determine whether apoptosis or necrosis of lens epithelial cells occurs after lens extraction.

METHODS

Lens extraction was performed on 24 rabbit eyes. The authors then performed terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and transmission electron microscopy on the eyes 1 to 10 days after surgery.

RESULTS

The postoperative lens was demarcated into three regions by the adhesion between the incised edge of the anterior capsule and the posterior capsule: the adhesive region, the intracapsular region, and the central portion of the posterior capsule. By day 2, TUNEL-positive cells with morphologic characteristics of necrosis were detected in the intracapsular region. Beginning on day 5, TUNEL-positive cells with morphologic characteristics of apoptosis and necrosis were detected in the adhesive region. Apoptotic cell death in this region was detected among the myofibroblast-like cells. Lens epithelial cells that had extended onto the central portion of the posterior capsule began to diminish on day 8 or 9, some of them morphologically demonstrating necrotic changes.

CONCLUSIONS

Apoptosis of lens epithelial cells occurs in the process of wound healing and reepithelialization after lens extraction, leading to secondary cataract. If the induction of apoptosis is better understood, protocols might be developed that could prevent reepithelialization through apoptosis, thus delaying or preventing secondary cataracts.

Keratinocytes become terminally differentiated in a process involving programmed cell death

Oral keratinocytes originate from basal cells, differentiate during migration to the surface, and finally are shed. Apoptosis occurs at the end of differentiation, but the precise relationship between terminal differentiation and apoptosis is not clear. In the present study, Bcl-xL was expressed in the basal cell and spinous cell layers, and Bax was expressed in the spinous cell and granular cell layers. In cultured keratinocytes, Bcl-xL was expressed under conditions of 0.1 mM calcium (low Ca2+) but disappeared under conditions of 1.0 mM calcium (high Ca2+); the latter induces keratinocyte differentiation. Bax was not expressed in keratinocytes with low Ca2+ but was expressed in cells with high Ca2+. Finally keratinocytes with high Ca2+ underwent apoptosis, which was detected by the TUNEL method and by 180-bp DNA fragmentation. These results suggest that the process of terminal differentiation in gingival epithelium is a pathway to apoptosis.

Neonatal sciatic nerve transection induces TUNEL labeling of neurons in the rat spinal cord and DRG

Transection of a peripheral nerve in neonatal rats induces an extensive death of axotomized neurons. We demonstrate here that spinal motoneurons and sensory dorsal root ganglia neurons become TUNEL-labeled after sciatic nerve transection in neonatal rats, thus indicating that apoptotic mechanisms are involved in the death process. Interestingly, there is also a profound increase of TUNEL-labeled interneurons in the deep dorsal horn. This location suggests that an intact afferent input and/or contact with target cells is essential for interneuronal survival. Death of motoneurons and sensory neurons could be a result of the injury per se and/or the deprivation of neurotrophic substances, secondary to the loss of contact with target cells.

Apoptosis in cultured human colon cancer cells induced by combined treatments with 5-fluorouracil, tumor necrosis factor-alpha and interferon-alpha

Biochemical analysis using nick end-labeling was performed to investigate the effect of various combinations of 5-fluorouracil, natural human tumor necrosis factor-alpha and natural human interferon-alpha on the induction of apoptosis in RPMI 4788 human colon cancer cells. After treatment with 5-fluorouracil (1 mM) for 48 h, the number of nick end-positive cells was significantly increased in comparison to the situation without treatment. When tumor cells were treated with 1 mM 5-fluorouracil, 2.86 Japan Reference Units (JRU)/ml natural human tumor necrosis factor-alpha and 1 x 10(3) IU/ml natural human interferon-alpha in combination for 48 h, the number of nick end-positive cells was significantly higher than that after treatment with 5-fluorouracil alone. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay revealed a significant decrease of relative viability, as compared to treatment with 5-fluorouracil (1 mM), 5-fluorouracil + natural human tumor necrosis factor-alpha, or 5-fluorouracil + natural human interferon-alpha for 48 h. Pretreatment with 5-fluorouracil (1 mM) for 24 h prior to treatment with natural human tumor necrosis factor-alpha (2.86 JRU/ml) and natural human interferon-alpha (10(3) IU/ml) for 24 h resulted in a significant increase of nick end-positive cells compared to pretreatment with natural human tumor necrosis factor-alpha and natural human interferon-alpha prior to treatment with 5-fluorouracil for 24 h (p < 0.05). These results suggest that 5-fluorouracil alone can induce apoptosis in RPMI 4788 tumor cells and that this effect can be enhanced by combination with natural human tumor necrosis factor-alpha and natural human interferon-alpha.

Epidermal apoptotic cell death in erythema multiforme and Stevens-Johnson syndrome. Contribution of perforin-positive cell infiltration

OBJECTIVE

To clarify the mechanism of epidermal cell death in erythema multiforme.

DESIGN

Retrospective study.

SETTING

Academic referral center.

PARTICIPANTS

Nine patients with Stevens-Johnson syndrome (SJS), 9 patients with Hebra disease (EMH), and 5 healthy volunteers.

INTERVENTIONS

Biopsy specimens were obtained from the border of the fresh lesions before treatment. Control specimens were obtained from normal skin.

MAIN OUTCOME MEASURES

Histopathological epidermal apoptosis detected with nuclear DNA fragmentation and counts of dermal immunoreactive perforin-positive infiltrates were compared between SJS and EMH.

RESULTS

Eight patients (89%) with SJS showed clear apoptosis with keratinocyte DNA fragmentation. All SJS samples had intensive perforin-positive dermal infiltrates. Only 3 patients (33%) with EMH showed apoptotic change, and it was to a far less extent with far less dermal perforin-positive infiltrates. Control specimens showed no apoptotic cells in the epidermis or expression of perforin in the dermis.

CONCLUSIONS

Perforin mediates apoptosis in the pathogenesis of the epidermal cell changes in SJS but not in EMH. In addition to the differences in clinical severity and histopathological conditions, our findings indicate a pathogenic difference between SJS and EMH.

Apoptotic cell nuclei favour aggregation and fluorescence quenching of DNA dyes

Apoptotic cell nuclei are known to stain hyperchromatically with absorption dyes and dimly with many DNA fluorochromes. We hypothesised that both optical phenomena have the same cause--the ability of apoptotic chromatin to aggregate cationic dyes. This hypothesis was tested using prednisolone-primed rat thymus, which is known to contain apoptotic cells. The apoptotic cells were classified as early and late, based on their morphology, in thin and semithin sections and in thymus imprints on slides. Direct reaction for DNA strand breaks (TUNEL) indicated the presence of breaks in both categories of cells, with more intense labelling in late apoptosis. The chromatin ultrastructure of early apoptotic cells initially retained the supranucleosomal order of packaging which characterises control cells, whereas the dense chromatin of late apoptotic cells possessed the degraded structure. Absorption spectra of the toluidine blue-stained early apoptotic cell chromatin revealed a metachromatic shift, indicating a change of DNA conformation and polymerisation of the dye. When the staining was performed by acridine orange (preceded by a short acid treatment), a paradoxical several-fold increase of fluorescence intensity at a several-fold dilution of the dye was found. The simultaneous reduction of the ratio of red to green components of fluorescence confirmed that the concentration-dependent fluorescence quenching was due to aggregation of the dye. The results suggest that the enhanced affinity of the chromatin of early apoptotic cells for cationic dyes is associated with conformational relaxation rather than degradation of DNA. In late apoptotic cells, the very dense packaging of degraded DNA promotes further aggregation of dyes. The results suggest alternative methods for detection and discrimination of early and late apoptotic cells.

Apoptotic and proliferating cells in cutaneous lymphoproliferative diseases

BACKGROUND

The cell production vs the cell loss rate in one of the most important parameters in evaluating growth and biological behavior of neoplasms. Individual cell disintegration in tissues, apoptosis, is a constant finding in various tumors and has been shown, by using several techniques, as a recognizable cell death that is different from necrosis.

DESIGN

We studied the apoptosis-proliferation ratio in various lymphoproliferative disorders in the skin, including mycosis fungoides (MF), cutaneous T-cell lymphoma showing solid tumor mass (CTCL), B-cell lymphoma of the skin (BCL), lymphomatoid papulosis (LyP), and cutaneous pseudolymphoma by using terminal deoxyuridine triphosphate (dUTP)-biotin nick end labeling (TUNEL), a newly developed method to detect internucleosomal breaks characteristic of apoptotic cells.

SETTING

University referral center.

PATIENTS

Fifty patients with cutaneous lymphoproliferative diseases.

MAIN OUTCOME MEASURES

Proliferation indexes and apoptosis index calculated by using immunohistochemical techniques.

RESULTS

The proliferation indexes in pseudolymphoma, which were calculated by using immunohistochemical analyses with anti-proliferating cell nuclear antigen and anti-MIB-1 monoclonal antibodies, were significantly lower than the indexes of MF, CTCL, BCL, and LyP, whereas, the apoptosis index in Lyp was significantly higher than in any other lymphoproliferative diseases studied. The apoptosis-proliferation ratio in the tumor stage of MF, CTCL, and BCL was almost constant, but the ratios in LyP and the plaque stage of MF were significantly higher than in the other diseases studied.

CONCLUSIONS

The clinical behavior of each lymphoproliferative disease in the skin seemed to be reflected in the apoptosis and proliferation indexes. We conclude that these indexes may become useful factors in the determination of the diagnosis and the prognosis for patients with lymphoproliferative diseases.

Detection of apoptosis in colorectal carcinoma by light microscopy and in situ end labelling

OBJECTIVE

An in situ end labelling reaction (ISEL) was recently described for the detection of apoptotic cells in histologic sections. We compared the efficiency and reproducibility of this assay with those of routine light microscopy using hematoxylin and eosin (H&E) in the quantitation of apoptotic cells in colorectal cancer.

STUDY DESIGN

Paraffin-embedded archival tissues from 15 colorectal carcinomas were used in the study. ISEL was performed using terminal deoxynucleotidyl transferase, biotinylated deoxyuridine triphosphate and streptavidin-alkaline phosphatase.

RESULTS

Apoptotic indices determined by the two assays showed a strong positive correlation (Pearson coefficient 0.82), with the ISEL assay detecting twice the number of apoptotic cells as that seen with H&E staining. Both assays showed significant interobserver and intraobserver variation, while the ISEL assay also showed considerable interassay variability and was less cost-effective than H&E in the detection of apoptotic cells.

CONCLUSION

In the light microscopic quantitation of apoptosis in colorectal tumors, the ISEL assay offered no greater reproducibility, and was less cost-effective, than routine H&E staining.

p53 accumulation and apoptosis in embolized meningiomas

Preoperative embolization of meningiomas is performed to decrease blood loss at surgery. While it is also expected to reduce tumor recurrence by producing necrosis at the site of dural attachment, very little has been described about what happens to the non-necrotic tumor cells. We investigated how the proliferative activities of meningiomas were modified after embolization. In nine meningiomas which were embolized preoperatively, proliferative potentials and expression of cell cycle inhibitors were assessed immunohistochemically using MIB-1, anti-53 (DO-1 and DO-7), and anti-p21 (WAF1/CIP1) monoclonal antibodies. To determine whether a cell underwent apoptotic death besides necrosis, we applied the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling method. Results were compared with control meningiomas without embolization. MIB-1 positive cells often gathered in perinecrotic areas, although the mean MIB-1 staining index of the embolized meningiomas was not significantly different from the control. p53 and its downstream effector p21 accumulated mainly in the perinecrotic areas in eight of the nine embolized meningiomas. Apoptosis was also observed in the concomitant areas. Double staining for both MIB-1 and p21 frequently showed positive cells for both antibodies. The accumulation of MIB-1 positive cells in the embolized meningiomas may not be a sign of fast growth or malignancy, but it may implicate arrest of cell cycle by the p21. This study indicates that embolized meningiomas exhibit not only necrosis but also apoptosis and cell cycle arrest. The latter effects appear to be at least partly p53 dependent.

Migration of granule neurons in cerebellar organotypic cultures is impaired by methylmercury

To examine whether abnormal migration of granule cells in the external granular layer during cerebellar development is in part of the etiology of fetal Minamata disease, organotypic culture of rat cerebellar slice was established. Migration of external granule cells pulse-labeled with bromodeoxyuridine (BrdU) toward the internal granular layer was inhibited by the presence of methylmercury (0-10 microM) in a dose-dependent manner. Nuclear condensation and DNA fragmentation visualized by the indirect immunofluorescence method with anti-BrdU antibody and the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) method indicated that a large fraction of cells in the external granular layer underwent apoptotic death in the slices treated with 10 microM methylmercury. Thus, methylmercury inhibits the migration of cerebellar granule cells in a model system for neural development. The impaired migration was a possible cause of the apoptotic death of external granule cells.