Transferase-mediated dUTP-digoxigenin Nick End Labeling Research Articles

Inhibition of nasal mucosal eosinophils after immunotherapy is associated with a decrease in interleukin-13 mRNA and vascular cell adhesion molecule-1 expression

Grass pollen immunotherapy is highly effective in reducing seasonal hay fever symptoms and medication requirements. Clinical improvement is accompanied by a reduction in nasal mucosal eosinophils, although the mechanism is unknown. Nasal biopsies were taken from 37 adults before immunotherapy and during the peak pollen season following 2 years treatment. Biopsies were processed for immunohistochemistry for CCR3, adhesion molecules (intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1) and apoptotic cells (terminal deoxyribonucleotidyl transferase-mediated dUTP–digoxigenin nick end-labeling; TUNEL), as well as for interleukin (IL)-4 and IL-13 mRNA-positive cells. Results were compared with eosinophil numbers in the nasal mucosa. Analysis of the clinical data confirmed that the proportion of patients who showed greater than 60% improvement in symptoms (47 and 15%) and in rescue medication (79 and 10%) were significant for the immunotherapy group compared with placebo group (P < 0.03 and P < 0.02, respectively). Seasonal increases were observed for VCAM-1 expression (P = 0.05) and IL-13 mRNA-expressing cells (P < 0.05) in the placebo group, but not in the immunotherapy group. The differences for VCAM-1 expression achieved significance between groups (P = 0.05). There was no significant difference in either ICAM-1 expression or in the number of CCR3 + cells, TUNEL + apoptotic cells and IL-4 mRNA-expressing cells. Successful grass pollen immunotherapy was associated with inhibition of seasonal increases in nasal eosinophils, IL-13 mRNA-expressing cells and VCAM-1 expression, but no change in CCR3 expression or in the number of apoptotic cells. The reduction in eosinophils after immunotherapy may be due to suppression of eosinophil recruitment to the nasal mucosa rather than enhanced apoptosis.

Tea consumption, apoptosis, and colorectal adenomas.

Induction of apoptosis has been suggested as a mechanism for the anti-carcinogenic effect of tea constituents in animals and in vitro studies. We addressed this hypothesis in a human study. Study participants were consecutive patients who underwent colonoscopy at the UNC Hospitals (August 1998 to March 2000). Biopsies were taken from normal rectal mucosa. Apoptosis was scored by the terminal deoxyribonucleotide transferase-mediated digoxigenin dUTP nick end labeling (TUNEL) method and by standard morphological criteria. The analysis included 171 patients with adenomas (cases) and 323 adenoma-free controls. After adjusting for sex, age, race, and BMI, apoptotic score was inversely associated with adenoma: the odds ratios (ORs) for linear trend associated with tertiles were 0.3 (0.3-0.5) for morphologic score and 0.5 (0.4-0.6) for the TUNEL score, respectively. Tea consumption (2-3 and >3 versus <2 servings/day) showed a weak negative association with adenoma: the ORs were 0.7 (0.3-1.4) and 0.5 (0.2-1.1), respectively. Neither measurement of apoptotic score changed by the level of tea consumption (P value for Kruskal-Wallis test > or =0.5). We did not find statistical interaction between apoptotic score and tea consumption. Tea exposure is not associated with apoptosis in normal rectal tissue in vivo.

Methylprednisolone inhibits low-flow hypoxia-induced mitochondrial dysfunction in isolated perfused rat liver.

To investigate the mechanism by which methylprednisolone protects the liver from hypoxia-induced injury. Prospective control study using the isolated rat liver. Animal research facility. Male, fasted, pathogen-free Sprague-Dawley rats. Low-flow hypoxia was produced by reducing afferent perfusate pressure from 10 to 2.5 cm H(2)O; isolated livers were portally perfused for 2 hrs. We measured mitochondrial membrane potential and hydrogen peroxide production by imaging rhodamine 123 and 2'-7'-dichlorofluorescein fluorescence, respectively. Leakage of mitochondrial enzymes was also monitored by assaying mitochondrial aspartate aminotransferase activity in the outflow perfusate, and the radical-scavenging effect of methylprednisolone was assessed by measuring luminol-dependent hydrogen peroxide chemiluminescence. Apoptosis in liver cells was determined by using terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling. Rhodamine 123 fluorescence was significantly diminished in the hypoxic liver, especially in the region of the terminal hepatic venules, which is indicative of membrane depolarization in the mitochondria in those areas. Hypoxia-induced mitochondrial dysfunction was indicated by leakage of aspartate aminotransferase into the outflow perfusate, and increased 2'-7'-dichlorofluorescein fluorescence indicated increased hydrogen peroxide levels, particularly in the midzone. Pretreatment with 30, 10, or 3 mg/kg of methylprednisolone inhibited the hypoxia-induced mitochondrial membrane depolarization and enzyme leakage, although hydrogen peroxide levels and apoptosis in sinusoidal endothelial cells were unaffected. Methylprednisolone does not protect the liver from hypoxia-induced injury by suppressing hydrogen peroxide production. Instead, the beneficial effect of methylprednisolone seems to be related to its ability to protect against mitochondrial membrane depolarization under hypoxic conditions.

Association of metallothionein expression and lack of apoptosis with progression of carcinogenesis in Barrett's esophagus.

Barrett's esophagus is the transformation of normal esophageal squamous epithelium to specialized intestinal metaplasia (SIM). Among the Barrett's specialized cells, those that can develop protective mechanisms against apoptosis may have potential to become malignant. Studies have shown that overexpression of metallothionein (MT), low molecular protein that protects cells from apoptotic stimuli, appears to be associated with more advanced, highly malignant tumors. We thus investigated the relationship between MT expression and apoptosis in different stages of Barrett's carcinogenesis. Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling and immunohistochemical dual-staining assay were performed in human biopsy samples of normal, SIM, dysplasia, and adenocarcinoma. Apoptotic index and MT expression were quantified by using an image system to analyze the converted digital data. A negative correlation between MT expression and apoptotic index was found. MT expression was significantly increased along with the histologic progression towards adenocarcinoma. This study thus suggests that MT may contribute to cytoprotection, thereby inhibiting apoptosis and leading to carcinogenesis of Barrett's esophageal cells.

Graded sensitiveness of the various retinal neuron populations on the glyoxal-mediated formation of advanced glycation end products and ways of protection

The accumulation of advanced glycation end products (AGEs) in retinal cells is known to be associated with the risk of diabetic retinopathy. To develop a model of AGE-related metabolic stress in retinal organ cultures, we investigated the accumulation of a typical glycoxidation product (N(epsilon)-[carboxymethyl] lysine [CML]) and its possible pro-apoptotic effects on different retinal cell populations. Retinal organ cultures (rat) were kept for 9 h in the Ames medium containing 0 (control), 5, 25, 50, 150, 300 and 800 micro M glyoxal. The expression of bax, active caspase-3, and the accumulation of CML were studied by using immunohistochemistry after the paraffin embedding of retinal explants. Apoptosis was studied using the terminal deoxynucleotidyl transferase-mediated dUTP digoxigenin nick end labeling (TUNEL) test and electron microscopy. Alpha lipoic acid (alpha-LA), sodium metavanadate (NaVO(3)), N-acetylcysteine (NAC), aminoguanidine (AG), and nicotinamide (NA) were used to influence glyoxal effects in organ cultures. In cultured normal non-diabetic retinae, small amounts of CML and the apoptosis-promoting factors bax and active caspase-3 were present. CML, bax and active caspase-3 increased after incubation with glyoxal. Incubation with glyoxal (<300 micro M, 9 h) increased apoptotic events in all layers. At low glyoxal concentrations, we found a graded sensitiveness of the different layers: at 25 micro M 39.4% in GCL, 28.2% in INL, 11.9% in ONL. After 800 micro M glyoxal, approximately 50% of the cells in all layers of the retina were apoptotic. In the ONL, this ratio was reduced by NaVO(3) (17%), by AG (27%), by NA (24.8%), by NAC (25.2%), and by alpha-LA (33.5%). In the INL, AG (25.9%) produced the best result. In the GCL, NAC, NaVO(3) and AG reduced apoptosis. A-LA had no significant protective effect. The glyoxal-induced rapid formation of CML shows the ability of our retina model to simulate AGE-related effects in vitro. The dose-dependent expression of apoptosis-promotor molecules indicates that the apoptosis-inducing machinery starts in most retinal cells within 9 h. The neurotoxicity of glyoxal-induced AGE formation was shown by the significantly increased rate of cell death in the retina. The significant decrease of apoptotic events (P<0.01) indicates that antioxidants and AGE formation blocker can exert a differentiated cytoprotection for each of the retinal cell layers.

Effect of ectopic epithelial tissue within the stroma on keratocyte apoptosis, mitosis, and myofibroblast transformation

The purpose of this study was to examine the effects of the epithelium on processes involved in stromal wound healing. Lamellar epithelial-stromal flaps were produced in rabbit corneas with a microkeratome. Peripheral corneal epithelial tissue, central corneal epithelial tissue, or no epithelial tissue (control) was introduced beneath the flap. Corneas were removed at time points from 4 hr to 1 month after surgery. Tissue sections were analyzed with immunocytochemistry for Keratin 3 (K3) to detect epithelial antigen, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling (TUNEL) assay to detect apoptosis, immunocytochemistry for Ki67 to detect cell proliferation, and immunocytochemistry for α-smooth muscle actin (SMA) to detect myofibroblasts. K3 was detected at the level of the interface from 4 hr to 1 month after surgery in corneas in which epithelial tissue was introduced, but not control corneas, with the exception of one that developed epithelial in growth. Keratocyte apoptosis was significantly higher at 4 hr after flap formation in both groups in which corneal epithelial tissue was introduced beneath the flap compared with controls. Keratocyte proliferation was significantly greater at 72 hr in corneas in which epithelial tissue was introduced beneath the flap compared to the controls. Corneas in which epithelial tissue was introduced into the interface, but not control corneas, had stromal cells expressing α-SMA in the stroma anterior and posterior to the interface at 1 week and 1 month after surgery. This was also noted in the control cornea in which there was epithelial ingrowth. Signals derived from the corneal epithelium promote keratocyte apoptosis. Keratocyte proliferation is higher in corneas that have lamellar surgery when epithelial tissue is introduced into the interface. Epithelium-derived signals also participate in the generation and/or maintenance of myofibroblasts in the corneal stroma.

Apoptosis of ocular surface cells in experimentally induced dry eye.

To evaluate to effect of experimental dry eye on ocular surface apoptosis. Aqueous tear production and clearance were inhibited by systemic administration of scopolamine and exposure to an air draft for 12 days in 4- to 6-week-old 129SvEv/CD-1 mixed white mice. Eyes and ocular adnexa were excised, cryosectioned, and evaluated for apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) assay, immunohistochemical assay for caspase-3 and poly(ADP-ribose) phosphate (PARP), and examination of nuclear morphologic changes by Hoechst DNA nuclear staining and transmission electron microscopy. The number of TUNEL-positive cells in the mice with induced dry eye was significantly increased compared with control mice in the following ocular regions: central corneal (P < 0.0014), peripheral corneal (P < 0.0001), bulbar conjunctival (P < 0.0021), and tarsal conjunctival (P < 0.0046) epithelia; tarsal conjunctival stroma (P < 0.0274); and lid margin (P < 0.0219, n = 4 in all cases). There were no significant differences observed between treated and control groups in the central corneal, peripheral corneal, or bulbar conjunctival stroma; meibomian glands; skin; retina-choroid; or episcleral regions. Immunohistochemistry for caspase-3 and poly(ADP-ribose) polymerase p85 fragment revealed increased immunoreactivity in regions of increased TUNEL positivity, particularly in the corneal and conjunctival epithelial cells. Ultrastructural morphologic changes consistent with apoptosis were observed in the conjunctival epithelial cells. Experimentally induced dry eye in mice causes apoptosis of cells in ocular surface tissues including the central and peripheral corneal epithelium, bulbar and tarsal conjunctival epithelia, tarsal conjunctival stroma, and lid margin. Apoptosis may play a key role in the pathogenesis of keratoconjunctivitis sicca and may be a therapeutic target for this condition.

Effect of flaxseed supplementation on prostatic carcinoma in transgenic mice

Objectives To investigate the effects of flaxseed supplementation on prostatic neoplasia in the transgenic adenocarcinoma mouse prostate (TRAMP) model. Methods A total of 135 male TRAMP mice 5 to 6 weeks old were randomized to a control group (AIN-76A diet) or an experimental group (AIN-76A diet plus 5% flaxseed by weight). One half of the mice in each group were treated for 20 weeks and the remainder for 30 weeks. At autopsy, urogenital tissues (four prostatic lobes, seminal vesicles, and emptied bladder), lungs, lymph nodes, and grossly abnormal tissues were collected for histologic evaluation. Results Of the control mice, 100% developed prostate cancer versus 97% of the mice in the flaxseed group. The tumor/urogenital weight was 3.6 ± 0.4 g in the controls versus 1.9 ± 0.2 g in the flaxseed-treated mice ( P = 0.0005). At 20 weeks, no significant difference in tumor grade was seen between the two groups; however, at 30 weeks, the flaxseed-treated mice had significantly less aggressive tumors than did the controls ( P = 0.01). The prevalence of lung and lymph node metastases was 13% and 16%, respectively, in the control mice versus 5% and 12%, respectively, in the experimental group (difference not significant). After 20 weeks of treatment, cellular proliferation (Ki-67) differed significantly between the control and experimental groups (38.1 ± 2.03 versus 26.2 ± 2.03; P <0.0001), and the apoptotic index (deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling) was 1.45 ± 0.14 versus 3.3 ± 0.31 ( P <0.0001). Similar differences were seen after 30 weeks of treatment. Conclusions A diet supplemented with 5% flaxseed inhibits the growth and development of prostate cancer in the TRAMP model.

Histological evaluation and in situ localization of apoptosis in fresh and cryopreserved ovarian tissue

Objective: Although apoptosis has significant impact on ovarian homeostasis and reproductive function, little is known about 1) the dynamics of this process; 2) the feasibility of using combined morphology and terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) for apoptosis detection and 3) the impact of cryopreservation on this process. We conducted this investigation to study these issues, using a porcine animal model.Design: Eight non-pregnant, adult, female farm pigs were utilized for this study. The bilateral oophorectomy was performed at the Cleveland Clinic Foundation Biological Resources Unit in accordance with their standard operating procedures.Materials/Methods: The ovarian tissues were divided into two parts; one part was immediately fixed while the other was cryopreserved using standard protocol for ovarian cortical strips. The cryopreserved specimens were subsequently thawed and then fixed in Bouin solution. All the specimens were sectioned, fixed and stained with H&E. Ovarian follicles were histologically categorized as healthy and atretic and evaluated for the presence of apoptosis. In situ examination of apoptosis was performed using TUNEL assay.Results: 1) Apoptosis was found in the atretic, but not in the healthy follicles; 2) the nuclei of the granulosa cells, but not those of theca or stromal cells, were TUNEL positive; 3) some cells with histological features of necrosis and apoptosis were TUNEL negative, and 4) the distribution of apoptosis was not different between cryopreserved tissue and freshly fixed tissue.Conclusions: 1) The presence of apoptosis in the atretic follicles suggests its involvement in follicular atresia; 2) necrosis may represent alternative pathway for granulosa cell death, and 3) combined histology and TUNEL assay is useful method in detecting apoptosis, and finally 4) cryopreservation does not affect the pattern of apoptosis in ovarian tissue.Supported by: None. Objective: Although apoptosis has significant impact on ovarian homeostasis and reproductive function, little is known about 1) the dynamics of this process; 2) the feasibility of using combined morphology and terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) for apoptosis detection and 3) the impact of cryopreservation on this process. We conducted this investigation to study these issues, using a porcine animal model. Design: Eight non-pregnant, adult, female farm pigs were utilized for this study. The bilateral oophorectomy was performed at the Cleveland Clinic Foundation Biological Resources Unit in accordance with their standard operating procedures. Materials/Methods: The ovarian tissues were divided into two parts; one part was immediately fixed while the other was cryopreserved using standard protocol for ovarian cortical strips. The cryopreserved specimens were subsequently thawed and then fixed in Bouin solution. All the specimens were sectioned, fixed and stained with H&E. Ovarian follicles were histologically categorized as healthy and atretic and evaluated for the presence of apoptosis. In situ examination of apoptosis was performed using TUNEL assay. Results: 1) Apoptosis was found in the atretic, but not in the healthy follicles; 2) the nuclei of the granulosa cells, but not those of theca or stromal cells, were TUNEL positive; 3) some cells with histological features of necrosis and apoptosis were TUNEL negative, and 4) the distribution of apoptosis was not different between cryopreserved tissue and freshly fixed tissue. Conclusions: 1) The presence of apoptosis in the atretic follicles suggests its involvement in follicular atresia; 2) necrosis may represent alternative pathway for granulosa cell death, and 3) combined histology and TUNEL assay is useful method in detecting apoptosis, and finally 4) cryopreservation does not affect the pattern of apoptosis in ovarian tissue. Supported by: None.

Paradoxical effects by preoperative oral low-dose tegafur administration in human gastric carcinomas: Enhanced apoptosis and increased intratumoral microvessel density

This study examined the effect of preoperative low-dose tegafur treatment in human gastric carcinomas. Among 55 patients with gastric carcinoma, 33 received an oral administration of tegafur 600 mg/body/day for 7 days before. Formalin-fixed, paraffin-embedded specimens were immunostained for Ki-67, P53, P21, CD34, Bax, VEGF, and dThdPase and also examined by the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling procedure. The apoptotic index (AI), Ki-67 labeling index (KI) and intratumoral microvessel density (IMVD) were counted. Mean AI and IMVD were 3.4+/-1.60 and 126.1+/-36.56 in the treated carcinomas, and 2.3+/-0.88 and 98.0+/-44.40 in the non-treated carcinomas, both values being significantly higher in the former (P<0.05). The treatment resulted in a significant increase of mean AI in the intestinal type, in the early, and in the P53-positive carcinomas (P<0.05), while the treatment brought a significant increase of IMVD in the diffuse type, in the early and in the P53-negative carcinomas (P<0.05, respectively). No significant difference was noted on the frequency of P53, P21, BAX, VEGF and dThdPase expressions between the two groups. Ki-67 expression did not correlate with any factors. Preoperative low-dose tegafur treatment resulted in a paradoxical effect; enhanced apoptosis and increased IMVD in human gastric carcinomas.

Chronic low-Ca/Mg high-Al diet induces neuronal loss.

To evaluate the causative role of environmental aluminum (Al) in the development of neurodegeneration in Kiiamyotrophic lateral sclerosis (ALS), we examined how chronic exposure to a low-Ca/Mg and high-Al diet induced neuronal loss and tau-related neuronal degeneration in experimental animals. Optical microscopic examination showed tau-positive cells, atrophic neurons with darkly stained cytoplasms or swollen perikarya in the cerebrum, hippocampus and the brainstem of mice fed a low-Ca/Mg high-Al diet (Group 3). The neuronal loss was found in the frontal and parietal cortices of the mice and was not due to a classical apoptosis as detected by the terminal de ynucl otidyl transferase-mediated dUTP-digoxigenin nick end-labeling (TUNEL) method. Neuronal degeneration and spheroid formation was also seen in the spinal cord of the Group 3 mice. The Morin fluorescence technique showed Al and Ca deposition in the cortical neurons and vessels in the basal ganglia of these mice. An electron microscopic examination showed intranuclear filamentous structures, intracytoplasmic vacuoles and/or darkly stained cytoplasm in the cortical neurons of Group 3 mice. These findings were seen in mice of the 11-month-experimental period and increased until the 25-month-experimental period. The present findings suggested that chronic exposure to a low-Ca/Mg high Al condition induced an accumulation of hyperphosphorylated tau in the cortical neurons, swelling of the neuronal cytoplasm and loss in the cerebrum and spinal cord of mice. Environmental factors such as a low-Ca/Mg high Al exposure might be one of the risk factors for the development of neuronal degeneration of ALS in the Kii Peninsula.

Pathways of Proximal Tubular Cell Death in Bismuth Nephrotoxicity

Colloidal bismuth subcitrate (CBS), a drug for treatment of peptic ulcers, has been reported in the literature to be nephrotoxic in humans when taken in high overdoses. To investigate the mechanism of bismuth nephropathy, we developed an animal model by feeding rats single doses of CBS containing 3.0 mmol Bi/kg body weight. Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling assay, immunostaining for active caspase-3, and electron microscopy showed that proximal tubular epithelial cells die by necrosis and not by apoptosis within 3 h after CBS administration. Exposure of the renal epithelial cell lines NRK-52E and LLC-PK1 to Bi3+ in citrate buffer served as an in vitro model of bismuth nephropathy. NRK-52E cells exposed to 100 μM Bi3+ or more died by necrosis, as was demonstrated by nuclear staining with Hoechst 33258 and flow cytometry using Alexa488-labeled Annexin-V and the vital nuclear dye TOPRO-3. Bismuth-induced cell death of NRK-52E cells was not prevented by the caspase-3 inhibitor z-VAD-fmk, whereas this inhibitor did prevent cisplatinum-induced apoptosis. Mitochondrial dysfunction and induction of free radicals were shown not to be involved in bismuth nephrotoxicity. The early time point of damage induction in vitro as well as in vivo and the early displacement of N-cadherin, as found in previous studies, suggest that bismuth induces cell death by destabilizing the cell membrane. In conclusion, we showed that high overdose of bismuth induced cell death by necrosis in vivo as well as in vitro, possibly by destabilization of the cell membrane.

Olfactory epithelium as a novel toxic target following an intravenous administration of vincristine to mice.

To delineate morphological characteristics of olfactory lesions induced by vincristine (VCR), a vinca alkaloid derivative with antitumor activity, male BALB/c mice were given a single intravenous injection of 1.95 mg/kg, an estimated 10% lethal dose (designated as day 1). The animals were serially sacrificed on days 2, 3, 5, 10, 15 and 60, and the nasal mucosa was examined histopathologically. Cell death was noted in the olfactory epithelia adjacent to the respiratory epithelia from days 2 to 5. Inflammatory responses were not detected throughout the observation periods. Cell death was identified as apoptotic by the terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) assay and electron microscopy. Mitotic figures and proliferating cell nuclear antigen (PCNA)-positive reactions were diffusely scattered in both the basal and sensory cells. On days 10 or after, no prominent histological abnormalities were noted in the olfactory epithelia, which suggests the aforementioned lesions were completely recovered. These results demonstrate that it is essential to perform histopathological evaluation of the nasal mucosa during an early preclinical stage for novel antitumor drugs, since olfactory lesions due to the certain compounds like VCR may not be detected by any other procedure.

Effect of mechanical vs dilute ethanol epithelial removal on keratocyte apoptosis and polymorphonuclear leukocyte migration.

To investigate keratocyte apoptosis and polymorphonuclear (PMN) cell infiltration to the corneal stroma after mechanical epithelial scraping and chemical de-epithelialization with 18% ethanol solution. Twelve New Zealand Albino rabbits (24 eyes) were randomly divided into three groups. Group A was the control group with no epithelial removal. Group B underwent a 7.5-mm mechanical epithelial removal with a blunt spatula. Group C underwent 7.5-mm chemical de-epithelialization with 18% ethanol-balanced salt solution. Corneas were stained with terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) assay after 24 h. Only nuclear staining in keratocytes was counted. Polymorphonuclear (PMN) leukocyte densities were also assessed by light microscopy. Mechanical de-epithelialization (group B) and chemical de-epithelialization with 18% ethanol (group C) showed no difference in keratocyte apoptosis compared with the control group. There was also no difference between groups B and C. Group B showed no difference in PMN leukocyte counts compared with the control group. But the number of PMN leukocytes observed in group C was significantly higher than those encountered in the corneas of the control group (P < 0.05) and group B (P < 0.05). Dilute alcohol induces more PMN cell infiltration when compared with mechanical de-epithelialization although there is no difference in the apoptosis rates.

Mechanisms involved in hydroxycamptothecin‐induced apoptosis of gastric cancer cells

OBJECTIVE: Hydroxycamptothecin (HCPT) is a unique antitumor drug that acts directly on topoisomerase I and inhibits its activity. However, the mechanism of HCPT‐induced apoptosis is unclear. In the present study, the mechanism of HCPT‐induced apoptosis in gastric cancer cells was investigated by detecting the expression of p53, c‐myc, bcl‐2, bcl‐xl and bcl‐xs genes in gastric cancer cells. METHODS: Apoptosis of gastric cancer cells (SGC‐7901, MKN‐45) was determined by terminal deoxyribonucleotidyl transferase‐mediated dUTP– digoxigenin nick‐end labeling (TUNEL) and flow cytometry. The mRNA and protein levels of the p53, c‐myc, bcl‐2, bcl‐xl and bcl‐xs genes were tested by reverse transcription–polymerase chain reaction analysis and immunocytochemical stain, respectively. RESULTS: Hydroxycamptothecin may induce apoptosis in different differentiated gastric cancer cells. The effect of HCPT‐induced apoptosis on gastric cancer cells was dependent on the dose of HCPT used and the time of exposure to HCPT. Both SGC‐7901 and MKN‐45 cells manifested some morphological features of apoptosis after 12 h exposure to HCPT, including cell shrinkage, nuclear condensation, DNA fragmentation and formation of apoptotic bodies. Some typical subdiploid peaks before the G0/G1 phase were observed. The apoptotic rates induced by 10 μg/mL HCPT in SGC‐7901 and MKN‐45 cells were 21.88 and 12.34%, respectively. The mRNA and protein levels of p53 and bcl‐2 were downregulated after treatment with HCPT in SGC‐7901 cells. However, the c‐myc, bcl‐xl and bcl‐xs protein levels were unchanged in SGC‐7901 cells. In MKN‐45 cells, the mRNA and protein levels of p53 increased after treatment with HCPT, whereas the protein levels of bcl‐2, c‐myc, bcl‐xl and bcl‐xs remained unchanged. CONCLUSIONS: Our results indicate that HCPT‐induced apoptosis in gastric cancer cells may be regulated through modulation of the expression of p53 and bcl‐2 genes.

Keratocyte apoptosis and corneal antioxidant enzyme activities after refractive corneal surgery.

Refractive corneal surgery induces keratocyte apoptosis and generates reactive oxygen radicals (ROS) in the cornea. The purpose of the present study is to evaluate the correlation between keratocyte apoptosis and corneal antioxidant enzyme activities after different refractive surgical procedures in rabbits. Rabbits were divided into six groups. All groups were compared with the control group (Group 1), after epithelial scraping (Group 2), epithelial scrape and photorefractive keratectomy (PRK) (traditional PRK: Group 3), transepithelial PRK (Group 4), creation of a corneal flap with microkeratome (Group 5) and laser-assisted in situ keratomileusis (LASIK, Group 6). Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling assay (to detect DNA fragmentation in situ) and light microscopy were used to detect apoptosis in rabbit eyes. Glutathione peroxidase (Gpx) and superoxide dismutase (SOD) activities of the corneal tissues were measured with spectrophotometric methods. Corneal Gpx and SOD activities decreased significantly in all groups when compared with the control group (P<0.05) and groups 2, 3 and 6 showed a significantly higher amount of keratocyte apoptosis (P<0.05). Not only a negative correlation was observed between corneal SOD activity and keratocyte apoptosis (cc: -0.3648) but Gpx activity also showed negative correlation with keratocyte apoptosis (cc: -0.3587). The present study illustrates the negative correlation between keratocyte apoptosis and corneal antioxidant enzyme activities. This finding suggests that ROS may be partly responsible for keratocyte apoptosis after refractive surgery.

Expression of Fas and Fas ligand in human gastric adenomas and intestinal-type carcinomas: correlation with proliferation and apoptosis.

Fas (APO-1/CD95), a member of the tumor necrosis factor/nerve growth factor receptor superfamily, mediates apoptosis in response to agonistic antibodies or Fas ligand (FasL) binding. Previous reports indicated an up-regulation of FasL in gastric carcinomas to evade host immune attack. Fas/FasL expression, however, has not been analyzed in terms of apoptosis and proliferation in gastric adenoma and carcinoma. This study was conducted on seven human gastric carcinoma cell lines, 47 gastric adenomas, and 75 intestinal-type adenocarcinomas (48 early and 27 advanced carcinomas). Fas/FasL expression was examined by immunohistochemistry, apoptosis by the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling (TUNEL) method, and Fas gene mutation by a reverse transcriptase (RT) polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and sequencing method. Fas and FasL expressions were noted in 18 (38.3%) and 17 (36.2%) adenomas, in 21 (43.8%) and 33 (68.8%) early carcinomas, and in 10 (37.0%) and 19 (70.4%) advanced carcinomas, respectively. The frequency of FasL expression was significantly higher in advanced carcinomas than in the early carcinomas and adenomas; in contrast, there was no significant difference in Fas expression among the three groups. The mean apoptotic index (AI) was 4.96+/-0.51 in the adenomas, 2.96+/-0.23 in the early carcinomas, and 1.67+/-0.17 in the advanced carcinomas. A significantly higher Al was noted in the lesions with Fas expression than in those without Fas expression in all three groups. No missense mutations of the Fas gene were detected in any of the gastric carcinoma cell lines, or in the gastric adenomas or carcinomas. Upregulation of FasL may correlate with the progression of gastric carcinoma. Apoptosis in gastric adenoma and carcinoma cells may occur via Fas-dependent and -independent pathways, but further clarification is needed.

The effects of the melatonin on ultraviolet-B irradiated cultured dermal fibroblasts

It has been reported that reactive oxygen species (ROS) and oxygen-derived free radicals are generated by ultraviolet (UV) radiation and various chemicals and their important roles in cellular damage and apoptosis are being increasingly recognized. Melatonin is a hormone with multiple functions in humans, produced by the pineal gland and stimulated by beta-adrenergic receptors. Melatonin has been shown to have photo protection properties, but there has been little progress toward identifying the specific mechanisms of its action. To clarify the role of melatonin as a free radical scavenger, in response to ultraviolet-B (UVB) irradiation, we investigated the effects of UVB and melatonin on cytotoxicity, lipid peroxidation, terminal deoxynucleotidyl transferase-mediated digoxigenin-dUTP nick end-labeling (TUNEL) assay and alteration of cell cycle in cultured skin fibroblast. Cell survival curves after UVB irradiation showed dose dependent decrement pattern by trypan blue exclusion assay. Only 56% of dermal fibroblasts were survived at 140 mJ/cm 2 UVB irradiation. The damage was associated with cell membrane lipid peroxidation, as shown by accumulation malondialdehyde (MDA). By pre-cultivation with melatonin (10 −9 M), a significant preventive effect was noted on the increase in the absolute number of surviving cells (up to 92.5% of cells were survived) and the levels of MDA were markedly decreased. These finding suggest significant correlation between an increase of lipid peroxide and cell viability. Morphological changes associated with apoptotic cell death were easily distinguished by TUNEL stain. Quantitative analysis of DNA content of skin fibroblasts was evaluated by flow cytometric analysis performed after vital staining with propidium iodide. UVB suppresses the G1 progression induced pre-G1 arrest leading to apoptotic changes of dermal fibroblast and those are blocked by melatonin pre-treatment. The results show the photodynamic effects of UVB that supposes the production of ROS and arrest the cell cycle. Melatonin, which have newly accepted as a potential UV protection properties, is effective membrane peroxidation inhibitor and prevent the pre-G1 arrest when present in relevant concentration during UVB irradiation.

Trichosanthin‐induced apoptosis in gastric cancer is related to the downexpression of bcl‐2

OBJECTIVE: To study: (i) the induction of apoptosis in gastric cancer cells by trichosanthin; and (ii) the relationship between apoptosis and the expression of bcl‐2. METHODS: During in vitro experiments, morphological studies and the terminal deoxynucleotidyl transferase‐mediated dUTP–digoxigenin nick end‐labeling (TUNEL) method were used to detect apoptosis in gastric adenocarcinoma cell line SGC‐7901 before and after trichosanthin treatment. An immunohistochemical staining method and northern blot hybridization were used to detect the expression of the apoptosis‐related gene bcl‐2 before and after trichosanthin treatment. RESULTS: When SGC‐7901 cells were treated with trichosanthin (0.1 μg/mL, 36 h), they presented some typical apoptotic morphological changes that were observed by fluorescent staining. These morphological changes included nuclear condensation and nucleosomal fragments forming a lunate body under the nuclear membrane. When SGC‐7901 cells were treated with trichosanthin (0.1 μg/mL) for 36, 42 or 48 h, TUNEL staining revealed a significant increase in the apoptotic index (AI), from 3.78 ± 1.11%, 3.98 ± 1.12% and 3.85 ± 1.08%, to 11.30 ± 2.33%, 10.22 ± 2.00% and 11.18 ± 1.85% (P &lt; 0.01), respectively. When SGC‐7901 cells were treated with trichosanthin (0.1 μg/mL, 32 h), immunohistochemical staining revealed a decreased expression of the bcl‐2 protein product: the staining density decreased from ++/+++ to –/+ (P &lt; 0.01). When SGC‐7901 cells were treated with trichosanthin (0.1 μg/mL, 24 h), northern blot hybridization showed a decreased expression of bcl‐2 RNA: hybridization decreased from 35.19 ± 2.34 to 22.27 ± 3.90 (P &lt; 0.01). CONCLUSIONS: Trichosanthin is able to induce apoptosis in gastric cancer. The apoptosis may be mediated by the downexpression of the apoptosis‐related gene bcl‐2.

Persistence of stable intragraft cell chimerism in rat liver allografts after drug-induced tolerance.

Drug-induced tolerance of rat liver allografts is well documented. We analyzed cellular events during immunosuppressive therapy on day (d) 10 and in the late phase (d 100) after transplantation to assess for characteristics in the intrahepatic leukocyte (IHL) population in the phase of tolerance. Lewis rats served as recipients of Dark Agouti rat livers. Temporary immunosuppression with either cyclosporine (CsA) monotherapy (3 mg/kg/d) or triple therapy that consisted of a subtherapeutic CsA dosage (0.25 mg/kg/d) and monoclonal antibodies directed against the interleukin-2 receptor (IL-2R, CD25) and the intercellular adhesion molecule-1 (ICAM-1, CD54) was administered from postoperative d 0 to d 13. Cell migration and cell activation within liver grafts was assessed by standard histology and flow cytometry. IHL apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL). Both CsA monotherapy and triple therapy prolonged liver allograft survival to more than 100 d and led to the induction of donor-specific tolerance. Untreated recipients rejected their allografts within 14 d. In both groups, donor-specific IHLs initially dropped to 18% to 25% on d 10, but they rebounded to as much as 40% on d 100 as a common characteristic of both groups. Within this population, donor-specific T cells were dominant. In both groups, increased numbers of activated (IL-2R+) CD8+ T lymphocytes were present on d 100. No accumulation of apoptotic IHL was observed on d 100. Their proportion was unchanged in the triple therapy group and slightly decreased in the CsA group compared to the syngeneic controls. The present study reveals that tolerant liver allografts are repopulated by donor-specific T lymphocytes. This phenomenon is independent of the type of applied immunosuppression. The persistence of activated CD8+ T cells in the phase of proven donor-specific tolerance on d 100 indicates that liver tolerance is associated with the state of a permanent intragraft immune activation. It seems that the coexistence of donor cells with infiltrating recipient cells within liver grafts, termed intrahepatic cell chimerism, is characteristic for tolerated liver allografts.