Impaired endothelial function in hypertensive elderly patients evaluated by high resolution ultrasonography

BACKGROUND

Multiple investigations both in experimental models and in middle-aged patients with essential hypertension have demonstrated impaired endothelium-dependent vasodilation.

OBJECTIVE

To determine whether hypertension exerts an additional negative effect on endothelial function of large arteries in hypertensive elderly patients who may already be affected by endothelial dysfunction due to aging.

PATIENTS AND METHODS

Thirteen elderly patients with hypertension (69 9 years of age [mean SD]) were compared with 13 matched healthy elderly subjects (72 6 years of age). High resolution vascular ultrasound was used to measure brachial artery responses to reactive hyperemia (with increased flow causing endothelium-dependent dilation) and to sublingual nitroglycerine (causing endothelium-independent dilation).

RESULTS

Flow-mediated diameter (FMD) was significantly impaired in the hypertensive elderly group (6.7 3.3% versus 13.3 3.8% in the control group, P<0.05). No significant difference could be found in nitroglycerine-induced dilation between the elderly control group (12.1 4.9%) and the hypertensive elderly (10.2 6.8%). On simple linear analysis, FMD was inversely correlated with age (r=-0.60, P=0. 03) in the healthy elderly group. FMD in the hypertensive elderly was inversely related to age (r=-0.41, P=0.04) and mean blood pressure (r=-0.67, P=0.01).

CONCLUSIONS

This study showed decreased FMD with aging even in the healthy elderly, with a further decline in hypertensive elderly compared with healthy elderly subjects. This impairment of FMD in the hypertensive elderly group was related to age and mean blood pressure, indicating that aging and hypertension may impair endothelial function in the brachial artery of elderly patients with hypertension.

Field trials of a rapid test for G6PD deficiency in combination with a rapid diagnosis of malaria

A rapid single-step screening method for detection of glucose-6-phosphate dehydrogenase (G6 PD) deficiency was evaluated on Halmahera Island, Maluku Province, Indonesia, and in Shan and Mon States, Myanmar, in combination with a rapid diagnosis of malaria by an acridine orange staining method. Severe deficiency was detected by the rapid test in 45 of 1126 volunteers in Indonesia and 54 of 1079 in Myanmar, but it was difficult to distinguish blood samples with mild deficiency from those with normal activity. 89 of 99 severely deficient cases were later confirmed by formazan ring method in the laboratory, but 5 with mild and 5 with no deficiency were misdiagnosed as severe. Of the samples diagnosed as mild and no deficiency on-site, none was found to be severely deficient by the formazan method. Malaria patients were simultaenously++ detected on-site in 273 samples on Halmahera island and 277 samples from Shan and Mon States. In Mon State, primaquine was prescribed safely to G6 PD-normal malaria patients infected with Plasmodium vivax and/or gametocytes of P. falciparum. The new rapid test for G6 PD deficiency may be useful for detecting severe cases under field conditions, and both rapid tests combined are can be useful in malaria-endemic areas, facilitating early diagnosis, prompt and radical treatment of malaria and suppression of malaria transmission.

Prognostic significance of progesterone receptor immunohistochemistry for lymph node metastases in endometrial carcinoma

OBJECTIVE

The aim of this study was to determine whether progesterone receptor (PR), estrogen receptor (ER), p53 protein, and proliferating cell nuclear antigen (PCNA) expression constitute independent prognostic factors for lymph node metastases in endometrial carcinoma using immunohistochemical techniques on hysterectomy and biopsy specimens.

METHODS

We evaluated the correlation between lymph node metastases and PR/ER immunohistochemistry, p53/PCNA expression, age, tumor grade, myometrial tumor invasion, cervical involvement, and ovarian metastases in a series of 99 cases of primary endometrial carcinoma surgically staged with systemic pelvic lymphadenectomy and para-aortic lymph node biopsy.

RESULTS

Lymph node metastases from endometrial carcinoma were statistically correlated with negative PR immunohistochemistry (P = 0.001), intense p53 expression (66% or more of the tumor cells stained, P = 0.003), deep myometrial tumor invasion (greater than one-half, P = 0.001), and cervical involvement (P = 0.001). Tumor grade showed borderline statistical significance for lymph node metastases (P = 0.058). On multivariate analysis, negative PR, intense p53 expression, and cervical involvement were significant prognostic variables for lymph node metastases (P = 0.0001, 0.0023, and 0.002, respectively). Immunohistochemical study indicated that the PR status on preoperative biopsy specimens and hysterectomy specimens was in good agreement, but p53 status was not. Age, ovarian metastases, ER immunohistochemistry, and PCNA expression were not significantly related to lymph node metastases.

CONCLUSION

PR immunohistochemistry appeared to be the most powerful prognostic factor associated with lymph node metastases in endometrial carcinoma, independent of other clinicopathological parameters.

Preoperative cervical cytology in endometrial carcinoma and its clinicopathologic relevance

OBJECTIVE

The aim of this study was to assess the significance of malignant or suspicious cervical cytology in preoperative identification of poor prognostic factors in endometrial carcinoma and to determine whether preoperative abnormal cervical cytology is an independent prognostic factor for endometrial carcinoma.

METHODS

We evaluated the correlation between preoperative cervical cytology and postoperative clinicopathologic findings, sites of metastasis, and receptor status from 99 surgically staged patients with endometrial carcinoma.

RESULTS

Sixty-eight patients (68.7%) had normal cervical cytology, 1 (1.0%) had atypical cytology suspicious for malignancy, and 30 (30.3%) had malignant cytology on preoperative cervical cytology. Malignant and suspicious cervical smears were statistically correlated with surgical stage (P = 0.001), histopathology (P = 0.010), tumor grade (P = 0.012), depth of myometrial tumor invasion (P = 0.001), cervical involvement (P = 0. 01), lymph node metastases (P = 0.002), adnexal metastases (P = 0. 012), progesterone receptor (P = 0.007), and estrogen receptor (P = 0.031). No association was found between preoperative cervical cytology and patients' age or peritoneal cytology. Univariate analysis showed that cervical cytology was related to survival (P = 0.018). However, multivariate analysis of cervical cytology, stage, grade, and myometrial invasion showed that preoperative cervical cytology was not a significant prognosticator for survival.

CONCLUSION

Patients with endometrial carcinoma who have malignant or suspicious cytology detected by preoperative cervical cytology are at increased risk of having known poor prognostic factors. However, positive preoperative cervical cytology itself does not appear to be an independent prognostic factor and probably should not influence treatment decisions in endometrial cancer.

Nordihydrocapsiate, a new capsinoid from the fruits of a nonpungent pepper, capsicum annuum

A new capsiate-like substance, named nordihydrocapsiate (1), has been isolated from the fruits of a nonpungent cultivar, CH-19 Sweet, of pepper (Capsicum annuum). The structure of 1 was determined to be 4-hydroxy-3-methoxybenzyl 7-methyloctanoate by spectroscopic methods.

Dobutamine stress echocardiography at 7.5 mg/kg/min using color tissue Doppler imaging M-mode safely predicts reversible dysfunction early after reperfusion in patients with acute myocardial infarction

Dobutamine stress echocardiography (DSE) is widely used to predict reversible left ventricular dysfunction, but evaluation by this method is subjective. The recently developed color tissue Doppler imaging (TDI) M-mode may permit objective and quantitative assessment of changes in wall motion induced by DSE. We tested the hypothesis that this new method can detect sensitively reversible dysfunction in the post-myocardial infarction setting. DSE with color TDI M-mode and conventional DSE were performed to predict reversible dysfunction in 53 patients at a mean of 3 days after infarction using 7.5 and 10 microg/kg/min of dobutamine. Follow-up regular echocardiography (4 weeks later) was used as the reference technique to define reversible dysfunction segments. To predict reversible dysfunction segments, the standard segmental wall motion score change on conventional DSE and the ratio of the segmental wall velocity difference at rest versus stress (7.5 and 10 microg/kg/ min) on DSE with color TDI M-mode (7.5-TDI-M and 10-TDI-M, respectively) were used. With 7.5 microg/kg/min of dobutamine, the sensitivity for predicting reversible dysfunction using color TDI M-mode (7.5-TDI-M) was significantly higher than that of conventional DSE (89% vs 73%, p <0.05) whereas specificities and predictive values were almost identical. With a 10-microg/kg/min dose, color TDI-M mode (10-TDI-M) and conventional DSE were not significantly different in predicting reversible dysfunction. With use of color TDI-M mode, regional wall motion during DSE was analyzed objectively and quantitatively. Moreover, combined TDI-M and conventional data were slightly superior to either mode alone. There were no arrhythmias during 7.5 microg/kg/min of dobutamine, but 9 arrhythmias occurred during the 10-microg/kg/min dose in patients with acute myocardial infarction. In conclusion, color TDI M-mode permits objective and quantitative assessment of regional ventricular wall motion and gives additional information for detecting reversible dysfunction in DSE. Improvement of sensitivity at a lower dose of dobutamine with color TDI-M mode may increase the safety of DSE in the post-myocardial infarction setting.

Allyl-containing sulfides in garlic increase uncoupling protein content in brown adipose tissue, and noradrenaline and adrenaline secretion in rats

The effects of garlic supplementation on triglyceride metabolism were investigated by measurements of the degree of thermogenesis in interscapular brown adipose tissue (IBAT), and noradrenaline and adrenaline secretion in rats fed two types of dietary fat. In Experiment 1, rats were given isoenergetic high-fat diets containing either shortening or lard with or without garlic powder supplementation (8 g/kg of diet). After 28 d feeding, body weight, plasma triglyceride levels and the weights of perirenal adipose tissue and epididymal fat pad were significantly lower in rats fed diets supplemented with garlic powder than in those fed diets without garlic powder. The content of mitochondrial protein and uncoupling protein (UCP) in IBAT, and urinary noradrenaline and adrenaline excretion were significantly greater in rats fed a lard diet with garlic powder than in those fed the same diet without garlic. Other than adrenaline secretion, differences due to garlic were significant in rats fed shortening, also. In Experiment 2, the effects of various allyl-containing sulfides present in garlic on noradrenaline and adrenaline secretion were evaluated. Administration of diallyldisulfide, diallyltrisulfide and alliin, organosulfur compounds present in garlic, significantly increased plasma noradrenaline and adrenaline concentrations, whereas the administration of disulfides without allyl residues, diallylmonosulfide and S-allyl-L-cysteine did not increase adrenaline secretion. These results suggest that in rats, allyl-containing sulfides in garlic enhance thermogenesis by increasing UCP content in IBAT, and noradrenaline and adrenaline secretion.

4F2 (CD98) heavy chain is associated covalently with an amino acid transporter and controls intracellular trafficking and membrane topology of 4F2 heterodimer

4F2, also termed CD98, is an integral membrane protein consisting of a heavy chain linked to a light chain by disulfide bond. We have generated a monoclonal antibody to the mouse 4F2 light chain and cloned the cDNA. It encodes a mouse counterpart of rat L-type amino acid transporter-1, and induces system L amino acid transport in Xenopus oocytes in the presence of 4F2 heavy chain. Transfection studies in mammalian cells have indicated that the 4F2 heavy chain is expressed on the plasma membrane on its own, whereas the 4F2 light chain can be transported to the surface only in the presence of 4F2 heavy chain. 4F2 heavy chain is expressed diffusely on the surface of fibroblastic L cells, whereas it is localized selectively to the cell-cell adhesion sites in L cells expressing cadherins. These results indicate that the 4F2 heavy chain is associated covalently with an amino acid transporter and controls the cell surface expression as well as the membrane topology of the 4F2 heterodimer. Although 4F2 heavy and light chains are expressed coordinately in most tissues, the light chain is barely detected by the antibody in kidney and intestine, despite the presence of heavy chain in a complex form. The results predict the presence of multiple 4F2 light chains.

Detection of Man5GlcNAc and related free oligomannosides in the cytosol fraction of hen oviduct

The presence of free oligomannosides in cytosol has been demonstrated by metabolic radiolabeling, and Manalpha1-2Manalpha1-2Manalpha1-3(Manalpha1-6)++ +Manbeta1-4GlcNAc was detected as the main free oligomannoside in Chinese hamster ovary cells [Kmiécik, D., Herman, V., Stroop, C.J.M., Michalski, J.C., Mir, A.M., Labiau, O., Verbert, A., and Cacan, R. (1995) Glycobiology, 5, 483-494]. In the present paper, the isomeric structures and amounts of oligomannosides in the cytosol fraction of hen oviduct were analyzed by pyridylamination and exoglycosidase digestion. Hen oviduct was used since our group has already characterized the cytosolic neutral alpha-mannosidase and endo-beta-N-acetylglucosaminidase obtained from the same source. The amounts of Man2GlcNAc, Man3GlcNAc, Man4GlcNAc, and Man5GlcNAc were 0.6, 0.6, 0.5, and 0.8 nmol/g tissue, respectively, but Man6GlcNAc-Man9GlcNAc were not detected. The isomeric structures of the Man3GlcNAc-Man5GlcNAc found were (Manalpha1-2)0-2Manalpha1-3(Manalpha1-6)Manbeta1 -4GlcNAc, which were compatible with the substrate specificities of cytosolic endo-beta-N-acetylglucosaminidase and neutral alpha-mannosidase, indicating that these enzymes participate in the formation of the oligomannosides present in the cytosol.

[An elderly patient with an insulinoma who had prolonged dementia-like symptoms]

A 77-year-old woman had suffered from memory disturbance and disorientation for two years before she was admitted to the hospital because of confusion. Her score on the Hasegawa dementia scale revised (HDS-R) was 12 points at the time of the first medical examination. No other abnormalities could be found except for a blood glucose concentration of 34 mg/ dl. A Magnetic Resonance Image (MRI) of the brain showed some small lacunae on both sides in the frontal white matter and basal ganglia. After hospitalization, glucose was administered and the blood glucose concentration increased, but the dementia-like symptoms did not resolve. She was discharged because the symptoms were too difficult to control in the general hospital. Although dementia-like symptoms were present even after discharge, they did not necessarily appear during fasting. Six months later she was rehospitalized. The insulin-blood sugar ratio was at least 0.3 and abdominal echogram showed a 1-cm tumor at the tail of pancreas. The pancreas tail was removed and the tumor cells were reacted with anti-insulin-antibodies. One month after the operation, the dementia-like symptoms had resolved. The HDS-R score was improved to 27 points (normal range) 40 days after the operation. The amount of the slow waves in the electroencephalogram decreased 5 months after the operation. The dementia-like symptoms observed in this case could be regarded as the Durchgangssyndrom of Wieck. This syndrome is observed transiently at the time of recovery of deterioration of disturbances of consciousness. But it is treatable. This patient was an interesting case that showed Durchgangssyndrom mimiking dementia associated with insulinoma.

Prognostic significance of progesterone receptor immunohistochemistry in endometrial carcinoma

OBJECTIVE

The aim of this study was to evaluate the prognostic significance of steroid hormone receptors in endometrial carcinoma using immunohistochemical staining for progesterone receptor (PR) and estrogen receptor (ER).

METHODS

We evaluated the correlation between PR/ER immunohistochemistry and age, clinical stage, tumor grade, myometrial tumor invasion, and disease-free survival in a series of 92 cases of endometrioid adenocarcinoma.

RESULTS

Fifty (54.4%) endometrial carcinomas were PR-positive and 44 (47.8%) were ER-positive. PR immunohistochemistry of endometrial carcinoma was statistically correlated with the International Federation of Gynecology and Obstetrics (FIGO) stage (I, II vs III, IV, P = 0.001), FIGO grade (G1 vs G2 vs G3, P = 0.007), the depth of myometrial tumor invasion (< or = 1/2 vs > 1/2, P = 0.006), and disease-free survival (living vs dead, P = 0.0025). In contrast, ER immunohistochemistry had significant correlations with the depth of myometrial tumor invasion (P = 0.026) and disease-free survival (P = 0.032). Multivariate analysis of PR/ER immunohistochemistry, stage, grade, and myometrial invasion showed that the PR immunohistochemistry was a significant prognostic factor for survival (P = 0.026).

CONCLUSION

PR/ER immunohistochemistry was significantly related to survival and PR immunohistochemistry appeared to be the most reliable means for predicting survival in endometrioid adenocarcinoma of the endometrium, independent of other clinicopathological parameters.

Effects of mesenchyme on epithelial tissue architecture revealed by tissue recombination experiments between the submandibular gland and lung of embryonic mice

Lung epithelium during morphogenesis maintains a sheet structure of polarized cells lining a lumen, in which E-cadherin, beta-catenin and tight junctional proteins are localized at the cell-cell contact sites. On the other hand, the submandibular gland epithelium at early stages of development forms a non-cavitated mass of cells where E-cadherin/beta-catenin are present on the entire cell surfaces and tight junctional proteins are almost absent or weakly scattered. In the present study, tissue recombination experiments were performed between the two organs to explore roles of mesenchyme in the architectural development of the epithelium. Homotypic recombinants of both submandibular gland and lung showed the tissue architecture as observed in the intact organs. In contrast, 11-day lung epithelium cultured with 13-day submandibular mesenchyme formed multilayers of cells with the lumen being less visible. It was accompanied by redistribution of E-cadherin/beta-catenin along the entire cell surfaces and by an irregular distribution of tight junctional proteins. A similar redistribution of these molecules was observed in 15-day lung epithelium cultured with the submandibular mesenchyme, although the epithelial sheet structure lining the lumen was formed. On the other hand, the tissue architecture of submandibular gland epithelium was little affected by lung mesenchyme, although the epithelium was flattened and showed branching morphogenesis.

Iron-dependent oxidation, ubiquitination, and degradation of iron regulatory protein 2: implications for degradation of oxidized proteins

The ability of iron to catalyze formation of reactive oxygen species significantly contributes to its toxicity in cells and animals. Iron uptake and distribution is regulated tightly in mammalian cells, in part by iron regulatory protein 2 (IRP2), a protein that is degraded efficiently by the proteasome in iron-replete cells. Here, we demonstrate that IRP2 is oxidized and ubiquitinated in cells before degradation. Moreover, iron-dependent oxidation converts IRP2 into a substrate for ubiquitination in vitro. A regulatory pathway is described in which excess iron is sensed by its ability to catalyze site-specific oxidations in IRP2, oxidized IRP2 is ubiquitinated, and ubiquitinated IRP2 subsequently is degraded by the proteasome. Selective targeting and removal of oxidatively modified proteins may contribute to the turnover of many proteins that are degraded by the proteasome.

Lung tumor induced by long-term inhalation or intratracheal instillation of diesel exhaust particles

A series of long-term inhalation studies of diesel exhaust and intratracheal instillation of diesel particles was conducted on female SPF F344 rats. A particulate but not gaseous component in the inhalation studies provoked inflammatory changes and tumors in the lung, and the intratracheally instilled particles showed similar findings. Adenoma and adenocarcinoma were the main histologic types of the tumors which developed and they showed the phenotype of surfactant apoprotein-producing cells, suggesting that the tumor cell origin was a Type II alveolar cell. The tumor incidence rate correlated with the cumulative concentration of inhaled particles per week and with the amount of particles deposited in the lung. In the instillation studies, the carbon core of diesel particles obtained after exhaustive extraction of tarry matter showed a slightly lower positive rate of lung tumor formation than the rate in untreated diesel particles, indicating an important role of carbon core in the diesel particle-induced tumor. In the intratracheal instillation studies, point mutation of K-ras oncogene was detected in a significant percentage in the tumor cells.

Human SPA-1 gene product selectively expressed in lymphoid tissues is a specific GTPase-activating protein for Rap1 and Rap2. Segregate expression profiles from a rap1GAP gene product

Mouse Spa-1 gene with a region homologous to the human rap1GAP gene is transcriptionally induced in the lymphocytes by mitogenic stimulation. Herein we have cloned a cDNA for its human counterpart. SPA-1 cDNA encodes a 130-kDa protein (p130(SPA-1)) consisting of proline-rich regions and rap1GAP-related domain followed by a coiled-coil stretch. Baculovirally expressed p130(SPA-1) exhibited GTPase-activating protein (GAP) activity for Rap1 and Rap2, but not for Ras, Rho, Cdc42, Rac, and Ran, with comparable specific activity to the rap1GAP gene product (p85/95(rap1GAP)). In the cells, p130(SPA-1) was mostly localized at the perinuclear membranous region co-localizing with Rap1 and Rap2. Expression of SPA-1 and rap1GAP genes tended to be segregate in various tissues, lymphoid tissues expressing abundant SPA-1 transcript without rap1GAP, while those such as brain, kidney, and pancreas exhibiting rap1GAP mRNA with little SPA-1. Promyelocytic HL-60 cells, which expressed p130(SPA-1) with little p85/95(rap1GAP) in uninduced state, showed progressive decline in p130(SPA-1) and conversely drastic increase in p85/95(rap1GAP) as they ceased from proliferation and differentiated into macrophages by 12-O-tetradecanoylphorbol-13-acetate. These results suggested that products of SPA-1 and rap1GAP genes, albeit comparable GAP activity for Rap1 and Rap2, functioned in the distinct contexts depending on cell types and/or states.

Prethrombotic state due to hypercoagulability in patients with permanent transvenous pacemakers

Venous thrombosis is a relatively usual but serious complication of permanent transvenous pacing. However, the pathogenesis has not been defined. To clarify underlying abnormalities in the coagulation-fibrinolysis system in patients with permanent transvenous pacemakers, we measured serum levels of fibrinopeptide A (FPA), thrombin-antithrombin III complexes (TATs), plasmin-alpha 2 plasmin inhibitor complexes (PICs), D-dimer (D-D), beta-thromboglobulin (beta-TG), and platelet factor 4 (PF4) in 53 patients with permanent transvenous pacemakers and 10 control subjects. The patients were divided into two groups, as follows, according to the presence of mural thrombus documented along the pacing lead(s) by digital subtraction angiography and transesophageal echocardiography: Group Th (-), patients without venous route thrombus; and Group Th (+), patients with venous route thrombus. FPA and TAT levels increased significantly even in Group Th (-), and further increased in Group Th (+) compared with control subjects (FPA: 7.5 +/- 4.9, 15.3 +/- 8.8 vs 3.0 +/- 1.4 ng/mL, respectively, P < 0.05; TAT: 2.9 +/- 1.3, 4.8 +/- 2.3 vs 1.7 +/- 0.6 ng/mL, respectively, P < 0.05). There were no differences in levels of D-D, PIG, beta-TG, and PF4 among control subjects, Group Th (-), and Group Th (+). These findings suggest that the hypercoagulable state appears in patients with permanent transvenous pacemakers, even without apparent venous thrombosis. The patients with permanent transvenous pacemakers are thought to be in the prethrombotic state even if they have no venous route thrombosis.

Talc and amosite/crocidolite preferentially deposited in the lungs of nonoccupational female lung cancer cases in urban areas of Japan

To analyze the correlation between asbestos lung burden and lung cancer, lungs of 211 female cases with and without lung cancer were examined. Phase-contrast microscopic (PCM) counting of ferruginous (FBs) and uncoated fibers (UFs), which had length longer than 5 microns and aspect ratios greater than 3:1, revealed a significantly higher level of FBs plus UFs in urban lung cancer cases than urban non-lung cancer cases (1380.5 vs. 550.3; p < 0.001). No difference was noted between rural lung cancer and non-lung cancer cases. Analytical electron microscopic studies identified various kinds of mineral fibers with an aspect ratio greater than 3:1 in the lung tissue including chrysotile, actinolite/tremolite, amosite/crocidolite, fibrous talc, mica, silica, iron, wollastonite, chlorite, kaoline, and others. The most frequently detected fibers were thin, short chrysotile fibers, most of which could not be found by PCM, followed by relatively thick, long actinolite/tremolite fibers, fibrous talc, and in a smaller number, amosite/crocidolite of intermediate length and width. Amosite/crocidolite and fibrous talc counts in urban lung cancer cases were greater than those of urban non-lung cancer cases, rural lung cancer, and rural non-lung cancer cases; these findings were consistent with PCM analysis. Therefore, it is suggested that fibers detected in PCM observation may be mainly amosite/crocidolite with some parts fibrous talc and that fibrous talc in urban environments may be another candidate for carcinogenic or cocarcinogenic factors of female lung cancer.

Involvement of reactive oxygen intermediates in spontaneous and CD95 (Fas/APO-1)-mediated apoptosis of neutrophils

Apoptosis is well known to be mediated by oxidative stress. To evaluate the functional role of reactive oxygen intermediates (ROI) produced by neutrophils, we compared the rates of apoptosis in neutrophils isolated from normal donors and from patients with chronic granulomatous disease (CGD), a hereditary defect in ROI production. Spontaneous cell death in CGD neutrophils in vitro was significantly inhibited relative to normal neutrophils. The acceleration of apoptosis induced by anti-Fas monoclonal antibody (MoAb) in CGD neutrophils was much slower than that seen in normal neutrophils. These findings suggest that the apoptosis of neutrophils may be mediated by endogenous oxidative products. This suggestion was confirmed by observation that apoptosis of normal neutrophils was markedly inhibited by reduction of intracellular levels of hydrogen peroxide (H2O2). The inhibition of apoptosis in normal neutrophils by adding catalase occurred regardless of the presence of anti-Fas MoAb. H2O2 increased both spontaneous apoptosis and Fas-mediated apoptosis of the CGD neutrophils in proportion to that seen in normal neutrophils. Although several factors that mediate the apoptosis of neutrophils remain to be determined, these results suggest that ROI are major mediators of the apoptosis in neutrophils and may be involved in Fas-mediated signal transduction pathway.