Inappropriate discharges by fourth generation implantable cardioverter defibrillators in patients with ventricular arrhythmias

The study prospectively investigated the incidence, cause and efficient management of inappropriate discharge by the fourth generation implantable cardioverter-defibrillator (ICD) system in 45 patients (mean age, 57+/-16 years). During the follow-up period of 27+/-17 months, 18 patients (40%) experienced one or more inappropriate therapies: sinus and supraventricular tachycardia (15 patients) and T wave oversensing (3 patients). In the 15 patients, re-programming of the tachycardia detection interval and/or additional treatment with beta-blocking agents were effective. In the 3 patients with T wave oversensing, the arrythmia was associated with an increase in T wave amplitude, change in T wave morphology and decreased R wave amplitude, and re-programming of the sensitivity of the local electrogram or changing the number of intervals to detect ventricular tachycardia decreased the number of inappropriate discharges in all 3 patients. In conclusion, inappropriate therapies are common problems in patients treated with the fourth generation ICD system, but most of them can be resolved using the dual-chamber ICD system. However, in patients with T-wave oversensing, it is difficult to avoid inappropriate discharge completely, even if the dual-chamber ICD system is implanted.

Novel synthesized trimannose conjugate induces endocytosis and expression of immunostimulatory molecules in monocytic leukemia cells

Macrophage mannose receptor (MMR) recognizes the pattern of carbohydrates exposed on microorganisms and mediates endocytosis in macrophages. We have synthesized glycoconjugate cationic polymers carrying 3,6-branched alpha-D-mannoside, a trimannose conjugate (TMC) with a high affinity for mannose-specific lectins. Culture with 10 microM TMC for 6 hours induced adhesion and aggregation in NKM-1, a human myelomonocytic leukemia cell line. TMC also stimulated the accumulation of fluorescein isothiocyanate (FITC)-dextran (FITC-DX). This accumulation seemed to be mediated by endocytosis via MMR because mannan, which specifically binds to MMR, inhibited FITC-DX accumulation. Expression of CD14, adhesion molecules, and costimulatory molecules was induced for 24 hours in NKM-1 and in fresh leukemia blasts from 4 patients with acute myeloid leukemia (AML) M4 and M5 subtypes (French-American-British classification). To clarify the binding mechanism, we compared mannose conjugates and a monomer of mannose regarding their effects on endocytosis and enhancement of CD14 and CD86 expression. A polymer of monomannose clusters with a lower affinity for lectins slightly stimulated exdocytosis, whereas a monomer of trimannose had no effect. These findings suggest that concatenation between MMR and TMC may play an important role in the activation of monocytic leukemia cells. TMC may become a good candidate to target MMRs of leukemia cells.

Supermolecular structure of the enteropathogenic Escherichia coli type III secretion system and its direct interaction with the EspA-sheath-like structure

Enteropathogenic Escherichia coli (EPEC) secretes several Esp proteins via the type III secretion system (secreton). EspA, EspB, and EspD are required for translocation of the effector proteins into host cells, in which EspB and EspD are thought to form a pore in the host membrane. Recent study has shown that EspA forms a filamentous structure that assembles as a physical bridge between bacteria and host cell surfaces, which then functions as a conduit for the translocation of bacterial effectors into host cells. To investigate the supermolecular structure of the type III secreton in EPEC, we partially purified it from the bacteria membrane and observed it via transmission electron microscopy. The EPEC type III secreton was composed of a basal body and a needle part and was similar to those of Salmonella and Shigella, except for a sheath-like structure at the tip of the needle. The length of sheath-like structures varied; it extended more than 600 nm and was 10 times longer than the Shigella needle part. The putative major needle component, EscF, was required for both secretion of Esp proteins and needle complex formation. Interestingly, elongation of the sheath-like structure was observed under constitutive expression of EspA but not of EscF. Furthermore, the transmission electron microscopy view with immunogold labeled anti-EspA antibodies clearly showed that EspA is a component of the sheath-like structure. This study revealed, to our knowledge for the first time, the supermolecular structure of the EPEC type III secreton and its direct association with the EspA-sheath-like structure.

Agents for the treatment of glycosphingolipid storage disorders

We have developed a series of inhibitors of glucosylceramide synthase that are structurally based on the parent compound D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP). These inhibitors provide useful tools for manipulating glycosphingolipid levels in cells and for elucidating questions associated with sphingolipid signaling. Recently, two highly active glucosylceramide synthase inhibitors, D-threo-3', 4'-ethylenedioxy-1-phenyl-2-palmitoylamino-3- pyrrolidino-1-propanol and D-threo-4'-hydroxy-1-phenyl-2-palmitoylamino-3- pyrrolidino-1-propanol, were designed, synthesized, and studied. These inhibitors markedly reduced glycosphingolipid levels in MDCK cells without any accumulation of intracellular ceramide and associated growth inhibition. Subsequently, each inhibitor was evaluated for its ability to lower glycolipid levels in virally transformed lymphoblasts from a patient with alpha-galactosidase A deficiency. Both compounds significantly reduced neutral glycosphingolipid levels in the lymphoblasts without any morphological changes and growth inhibition. Furthermore, the inhibitors were applied to a mouse knockout model of Fabry disease. Inhibitor treatment blocked accumulation of globotriaosylceramide (Gb3) in the kidney, liver and heart of mice. In contrast to another glucosylceramide synthase inhibitor, N-butyldeoxynojirimycin, this treatment was not associated with any significant change in body weight or organ weight and without immunodepletion. These results suggest that these newest PDMP homologues are promising as therapeutic agents for the treatment of glycosphingolipid storage disorders.

Correlation between the effective refractory period and activation-recovery interval calculated from the intracardiac unipolar electrogram of humans with and without dl-sotalol treatment

In experimental studies and/or human body surface mapping, the activation-recovery interval (ARI) is used as a parameter to estimate local repolarization. However, it has not been clarified whether the ARI calculated from the intracardiac unipolar electrogram of humans reasonably represents the local effective refractory period (ERP). Measurement of ARIs at multiple ventricular sites can be helpful in assessing the dispersion of ventricular refractoriness of humans, so we examined the relationship between ERP and ARI in the control state and under treatment with dl-sotalol during clinical electrophysiologic studies (EPS). Of 19 patients, an EPS was performed in the control state in 12 and during treatment with dl-sotalol in the other 7. Quadripolar electrode catheters with an interelectrode distance of 5 mm were placed at the right atrium and in the right ventricle. Using atrial pacing, the heart rate was increased incrementally by 10 beats/min, and ERP and ARI were measured for each pacing rate. The ERP at the right ventricle was measured by single extrastimulation between the first and third distal electrodes of the catheter in the right ventricle, and the ARI was calculated from the second distal unipolar electrode of the same catheter as the interval between the minimum derivative of the intrinsic deflection and the maximum derivative of the T wave. In all patients, the unipolar electrogram was stable during the entire EPS, and 83 data points in the control group and 50 in the dl-sotalol group were analyzed. At each pacing rate, the beat-to-beat difference of ARI was less than 10 ms. As the atrial pacing rate increased, the ERP and ARI were progressively shortened, and linear regression analysis revealed an excellent correlation between ERP and ARI. At the same pacing rate, the ERP and ARI in the dl-sotalol group were longer than those in the control group, but no difference was observed in the slope (close to 1.0) and in the intercept of the regression lines between ERP and ARI. In the human ventricle, the ARI calculated from the intracardiac unipolar electrogram represents the local ERP both in the control state and under treatment with dl-sotalol. The ARI can be used as a parameter of local refractoriness and used to study the distribution of refractoriness in the human ventricle.

Inappropriate discharges from an intravenous implantable cardioverter defibrillator due to T-wave oversensing

This report describes the clinical management of 2 patients with ventricular fibrillation (VF) who received inappropriate shocks from an implantable cardioverter defibrillator (ICD) due to T-wave oversensing. Cardiac sarcoidosis was confirmed as the underlying heart disease in 1 patient and idiopathic dilated cardiomyopathy in the other. Within 2 months after ICD implantation, both patients received several inappropriate shocks during sinus rhythm. Stored electrograms showed decreased R-wave amplitudes and increased T-wave amplitudes. The ICD sensed both R- and T-waves as ventricular activation, which met the rate criteria for VF treatment. Reprogramming the sensing threshold in association with administration of a drug to slow the heart rate decreased the incidence of the inappropriate shocks in both patients, but these palliative measures did not completely suppress the inappropriate shocks. To avoid T-wave oversensing, the repositioning or adding of a sensing lead is required. The potential risk of T-wave oversensing in ICD patients who have small R-wave amplitudes should be recognized.

Isogenic strain of Escherichia coli O157:H7 that has lost both Shiga toxin 1 and 2 genes

An Escherichia coli O157:H7 strain isolated from a patient with hemorrhagic colitis was found to exhibit two slightly different colony morphology types on differential medium. Each morphological type, designated TT12A and TT12B, was isolated, and serological testing using various assays confirmed that both strains carried the O157 and the H7 antigens. Biochemical testing showed that the strains had identical profiles on AP120E analysis and, like typical O157:H7 strains, did not ferment sorbitol or exhibit beta-glucuronidase activity. Analysis with a multiplex PCR assay showed that TT12B did not carry the gene for either Shiga toxin 1 (Stx1) or Stx2, whereas these genes were present in TT12A and the toxins were produced. Apart from that, both strains carried the +93 gusA mutation, the cluster I ehxA gene for enterohemolysin, and the eae gene for gamma-intimin, which are all characteristics of the O157:H7 serotype. Phenotypic assays confirmed that both strains exhibited enterohemolysin activity and the attachment and effacing lesion on HeLa cells. Multilocus enzyme electrophoresis analysis showed that the strains are closely related genetically and belong in the same clonal group. Pulsed-field gel electrophoresis (PFGE) typing of XbaI-digested genomic DNA revealed that the two strains differed by two bands but shared 90% similarity and clustered in the same clade. All other non-Stx-producing O157:H7 strains examined clustered in a major clade that was distinct from that of Stx-producing O157:H7 strains. The findings that TT12B was identical to TT12A, except for Stx production, and its PFGE profile is also more closely related to that of Stx-producing O157:H7 strains suggest that TT12B was derived from TT12A by the loss of both stx genes.

Characterization of simple and reproducible vascular stenosis model in hypercholesterolemic hamsters

The importance of low-density lipoprotein (LDL) in the etiology of atherosclerosis is well recognized. We have established a reproducible stenosis model in hypercholesterolemic hamsters, and the process of arterial stenosis by thrombus or neointima was studied and compared with that in normal hamsters. The level of plasma LDL was 4.6 times higher in hamsters fed a high-cholesterol diet than in hamsters fed normal food. Endothelial injury in right common carotid arteries was induced using a modified catheter. Arterial blood flow was monitored continuously using a Doppler flow probe. Arterial patency after the initiation of injury in high-cholesterol hamsters was significantly changed as compared with that of normal hamsters. Neointima was observed 2 wk after the vascular injury. The neointimal area of high-cholesterol hamsters was significantly larger than that of normal hamsters. To characterize the stenosis in hypercholesterolemic hamsters, we measured platelet aggregation, thrombin time, activated partial thromboplastin time, and proliferating smooth muscle cells (SMC) in vitro and in vivo. The half-maximal inhibitory concentration value for platelet aggregation induced by thrombin or collagen, the DNA synthesis stimulated by platelet-derived growth factor (PDGF)-BB, and 5-bromo-2-deoxy-uridine labeling indices (proliferating index of SMC in vivo) in high-cholesterol hamsters were each significantly higher than the comparable value from normal hamsters. However, specific binding of PDGF-BB in SMC was not different between the two types of hamsters. Furthermore, we investigated the inhibitory effects of probucol or losartan on neointima formation using this model. Probucol, but not losartan, significantly reduced the neointimal area in hypercholesterolemic hamsters. These findings indicated that high levels of plasma LDL strongly contributed to the development of thrombus and neointima formation via both up-regulation of platelet aggregation and the enhancement of SMC proliferation. This stenosis model may be useful for the investigation of hypercholesterolemia-associated cardiovascular diseases.

Mucinous adenocarcinoma of Bartholin gland treated with radiation therapy: a case report

Adenocarcinoma of Bartholin gland is a very rare disease and its molecular pathological features are poorly delineated. A 92-year-old woman with mucinous adenocarcinoma of Bartholin gland with metastasis to the right inguinal lymph node was treated with radiation therapy alone. Despite intensive radiation therapy, the tumor was locally recurrent and the patient died 10 months after radiation therapy. We searched for the presence of human papillomavirus 16 and 18 DNA and the expression of p53 protein, CA19-9, CEA and MIB-1 antigen. Immunohistochemical study showed that mucinous adenocarcinoma of Bartholin gland produced CA19-9 and CEA.

Functional analysis of the type III secretion system in enteropathogenic Escherichia coli O157:H45

A mass outbreak of Escherichia coli O157:H45 was first reported in Japan in 1998. This pathogen was classified as an enteropathogenic E. coli (EPEC) O157 because it was characterized by the Shiga toxin gene (stx)-negative and bundle-forming pilus (bfp) gene-positive genotypes. In this study, we investigated the type III secretion system in EPEC O157. Although no type III secreted proteins, Esps (E. colisecreted proteins), in EPEC O157:H45 were detectable in culture supernatant, secreted proteins were induced by the introduction of an EPEC plasmid-encoded regulator, per. In further contrast to EHEC O157:H7, EPEC O157:H45 triggered the accumulation of tyrosine phosphorylated proteins beneath the adherent bacteria. These results suggest that regulation of the type III secretion apparatus and host signal transduction events between E. coli O157:H45 and O157:H7 are completely different.

The T lymphocyte structure CD60 contains a sialylated carbohydrate epitope that is expressed on both gangliosides and glycoproteins

The CD60 antigen is expressed on a majority of T cells in autoimmune lesions, and anti-CD60 can activate T lymphocytes. CD60 has been defined as the GD3 ganglioside, and subsequently as the 9-O-acetylated form of GD3. However, other evidence suggests that anti-CD60 recognizes a glycoprotein or family of glycoproteins expressed by T lymphocytes. The current studies were undertaken to better define the identity of the CD60 antigen on both T cells and non-T cells. Treatment of intact cells with neuraminidases of various specificities confirmed that detection of the CD60 epitope depends on expression of an alpha2, 8-disialic acid carbohydrate linkage, as is found in GD3 and related gangliosides. However, the sialicacid polymer colominic acid inhibited anti-GD2 and anti-GD3, but not anti-CD60 from binding to cell surfaces. Expression of CD60 did not correlate with expression of GD3 on a variety of cell lines and T cell populations. Expression of CD60 and 9-O-acetyl-GD3 was roughly parallel on some non-T cell lines such as melanoma cells, but on T cells expression of CD60 was consistently greater. Antibodies to GD2, GD3 and 9-O-acetyl-GD3 were ineffective at inhibiting binding of anti-CD60 to CD60+ cells. Activation responses of T cells to anti-CD60 were inducible in either the presence or absence of a response to anti-GD3. A novel inhibitor of glucosyl ceramide synthesis, D-threo-1-phenyl-2-palmitoylamino-3-pyrrolidino-1-propanol (D-t-P4) reduced expression of GD3 much more than CD60 on activated T lymphocytes. Following biotinylation of HUT78 T cells, anti-CD60 immunoprecipitated a 70 kDa antigen. Taken together, the present data and previous findings suggest that anti-CD60 can recognize both a modified form of the GD3 ganglioside and a carbohydrate-dependent complex epitope present on one or more glycoproteins. This glycoprotein epitope may be the more abundant and functionally significant CD60 antigen on T lymphocytes, while 9-O-acetyl-GD3 is likely to be the principal structure recognized by anti-CD60 on melanoma cells. These findings emphasize the complexity of understanding the functional roles of carbohydrate epitopes in cell activation.

Prevention of growth of human lung carcinoma cells and induction of apoptosis by a novel phenoxazinone, 2-amino-4,4alpha-dihydro-4alpha,7-dimethyl-3H-phenoxazine-3-one

Anti-tumor effects of a novel phenoxazinone, 2-amino-4,4-dihydro-4alpha,7-dimethyl-3H-phenoxazine-3-one (Phx), which was synthesized by the reaction of 2-amino-5-methylphenol with bovine hemoglobin, were studied in terms of suppression of the proliferation of human lung carcinoma cells and apoptosis induction. When Phx was added to cultures of the human lung carcinoma cell lines A549 (adenocarcinoma) and H226 (squamous carcinoma), it caused the growth inhibition and the death of these cells. Phx also fragmented the DNA of these cells to oligonucleosomal-sized fragments, which is characteristic of the apoptosis, dependent on the dose and exposure time. The cellular death caused by the administration of Phx was partially reversed by the addition of Z-VAD-fmk, a caspase family inhibitor. Present results suggest that Phx demonstrates anti-cancer activity against human lung carcinoma cell lines A549 and H226, by inhibiting growth and inducing apoptosis.

High Toxoplasma seroprevalence associated with meat eating habits of locals in Nepal

A serosurvey of Toxoplasma gondii infection in apparently healthy subjects (n = 404) living in Achham (n = 215) and Dang (n = 189) districts in western Nepal was carried out. An interview with 249 participants, each representing a household, was also conducted. This interview pertained to their meat eating habits and the keeping of cats in their houses. Toxoplasma antibodies were detected by using the microlatex agglutination test. The overall seroprevalence was 65.3% with no significant difference in the two districts (Achham: 66.9% and Dang: 63.5%) included (p = 0.546). Females and the Indo-Aryan ethnic-group showed marginally higher prevalence compared with their male (p = 0.545) and Tibeto-Burman (p = 0.075) counterparts. The majority of the infections was found to have occurred during childhood. The frequency of meat eating in western and eastern regions differed greatly (p = 0.000) with the people in the eastern region being frequent meat eaters than those in the western region. About one-third of the subjects, all Indo-Aryans, in the western region had the raw meat eating habit but none in the eastern region. Approximately 7.0% of households in both western and eastern regions kept cats. The present findings demonstrated a typical role of meat eating habits of people in the high Toxoplasma seroprevalence in Nepal.

Pulmonary receptors in reptiles: discharge patterns of receptor populations in snakes versus turtles

This study examines the effects of lung inflation/deflation with and without CO2 on the entire population of pulmonary receptors in the vagus nerve in two species of snakes and two species of turtles. We asked the question, "how does the response of the entire mixed population of pulmonary stretch receptors (PSR) and intrapulmonary chemoreceptors (IPC) in species possessing both differ from that in species with only PSR"? This was studied under conditions of artificial ventilation with the secondary goal of extending observations on the presence/absence of IPC to a further three species. Our results indirectly illustrate the presence of IPC in the Burmese python and South American rattlesnake but not the side necked turtle, adding support to the hypothesis that IPC first arose in diapsid reptiles. In both species of snake, CO2-sensitive discharge (presumably from IPC) predominated almost to the exclusion of CO2-insensitive discharge (presumably arising from PSR) while the opposite was true for both species of turtle. The data suggest that for animals breathing air under conditions of normal metabolism there is little to distinguish between the discharge profiles of the total population of receptors arising from the lungs in the different groups. Interestingly, however, under conditions of elevated environmental CO2 most volume-related feedback from the lungs is abolished in the two species of snakes, while under conditions of elevated metabolic CO2, it is estimated that volume feedback from the lungs would be enhanced in these same species.

Constitutive kinase activation of the TEL-Syk fusion gene in myelodysplastic syndrome with t(9;12)(q22;p12)

The TEL gene on 12p12-13 is a target for a number of translocations associated with various hematological malignancies. The fusion of the TEL gene to the Syk gene in a patient with myelodysplastic syndrome (MDS) with t(9;12)(q22;p12) is reported. Southern blot analysis of patient bone marrow cells with TEL and Syk gene probes detected rearranged fragments. Anchored polymerase chain reaction identified the Syk gene, a nonreceptor tyrosine kinase, on 9q22 fused downstream of TEL exon 5. The TEL gene was fused in-frame to Syk and produced a fusion protein that was constitutively phosphorylated in tyrosine with dimerization that was mediated by the helix-loop-helix domain of TEL. A TEL-Syk fusion product transformed the murine hematopoietic cell line BaF3 to interleukin-3 growth factor independence. TEL-Syk is a novel transforming protein and leads to the transformation of hematopoietic cells. These data implicate that the rearranged Syk gene is involved in the pathogenesis of hematopoietic malignancies.

Correlation of tissue and plasma RANTES levels with disease course in patients with breast or cervical cancer

The beta-chemokine RANTES was measured in plasma in 43 patients with breast cancer and in 23 patients with cervical cancer, and the RANTES content in primary tumors, tumor metastatic to lymph nodes, and clinically normal skin or pelvic mucosa was measured. In addition, plasma levels were determined in all of the patients for the platelet-derived chemokine beta-thromboglobulin (beta-TG) and for IFN-gamma, interleukin (IL)-2, IL-4, IL-5, and IL-10, along with serum IgE levels and blood eosinophils. Plasma RANTES levels were found to be higher in order of stages IV, III, II, and I of each cancer except for stage I. A marked increase in plasma RANTES level (> 10,000 pg/ml) was found in 27% of patients with progressive malignancy but in none of those in clinical remission. The platelet RANTES content was correspondingly decreased in those patients with increased plasma RANTES levels. Beta-TG showed a pattern similar to RANTES both in plasma and platelets, but with much less dramatic differences between patients with different stages of disease. Other allergic parameters, IgE, eosinophils and plasma IFN-gamma, IL-2, -5, and -10, were not elevated in the cancer patients. The RANTES content was markedly elevated in the primary tumor and metastatic lesions (lymph node or skin) from all of the patients with breast or cervical cancer, irrespective of the plasma RANTES level. In addition, in patients with progressive breast or cervical cancer, but not in patients thought to be cured of these tumors, the RANTES content was markedly increased in clinically normal tissue taken from near the operative site several months postoperatively, as well as in intact skin or mucosa taken perioperatively near the excised tumor. This study suggests an as-yet-undefined but important role played by RANTES in carcinogenesis, as well as the possibility that a RANTES assay in tissue surrounding a tumor or postoperative tumor site may help predict prognosis in these patients.

Long-term evaluation of extracorporeal shock-wave lithotripsy for cholesterol gallstones

BACKGROUND

Extracorporeal shock-wave lithotripsy (ESWL) is a treatment that preserves the gallbladder. Problems after ESWL treatment include stone recurrence and the development of biliary symptoms.

METHODS

Two hundred and sixty-two patients with cholesterol-type gallstones, the best indication for ESWL treatment, and 42 control patients with cholesterol-type gallstones who received no treatment entered this study. We evaluated the factors associated with recurrence of gallstones after stone clearance and the development of biliary symptoms after ESWL treatment.

RESULTS

The 3-, 5- and 7-year cumulative probabilities of gallstone recurrence were 20.6, 27.1 and 33.1%, respectively, with the recurrence probability significantly lower in patients with good gallbladder contractility. In patients with recurrence, ursodeoxycholic acid (UDCA) treatment was effective. In 69 patients with residual gallstones, the 3-, 5- and 7-year cumulative risks of biliary symptoms were 17.3, 24.9 and 30.5%, respectively. With residual gallstones, the risk of biliary symptoms developing was significantly lower in patients with a < or = 3 mm fragment size at the end of ESWL treatment and in those treated consistently with UDCA for 6 months or more after treatment with ESWL. The risk of biliary symptoms was significantly lower in ESWL-treated patients with residual stones who had a < or = 3 mm fragment size after treatment compared to those of control patients.

CONCLUSIONS

Ursodeoxycholic acid was effective in clearing stones in patients with gallstone recurrence. In patients with residual stones, the fragmentation of stones to < or = 3 mm and UDCA administration effectively reduced the risk of subsequent biliary symptoms.

omega-hydroxylation activity toward leukotriene B(4) and polyunsaturated fatty acids in the human hepatoblastoma cell line, HepG2, and human lung adenocarcinoma cell line, A549

The addition of glucose to the culture medium of HepG2 or A549 cells for 22 h caused a dose-dependent increase in leukotriene B(4) omega-hydroxylation activity in the homogenate. The addition of genistein to the culture medium of HepG2 or A549 cells for 22 h caused a dose-dependent decrease in the activity, although the number of living cells was not influenced by the addition of genistein. The inhibition by genistein was reversed by removal of genistein from the culture medium in 22 h. The specific leukotriene B(4) omega-hydroxylation activity was high in the nuclear envelope fraction of HepG2 or A549 cells, and a large portion of the activity was concentrated in the nuclear envelope fraction. In the nuclear envelope fraction, leukotriene B(4) omega-hydroxylation activity was accompanied by high polyunsaturated fatty acid omega-hydroxylation activity. The apparent K(m) values for arachidonic acid and leukotriene B(4) in the fractions of HepG2 or A549 cells were 25 and 50 microM, or 22 and 66 microM, respectively. The V(max) values were 222 and 104 pmol/min/mg protein, or 175 and 370 pmol/min/mg protein, respectively. NADPH-dependent omega-hydroxylation of LTB(4) in the nuclear envelope fraction of HepG2 or A549 cells was strongly inhibited by metyrapone and CO. The expression of cytochrome P450 4F2 mRNAs was detected in HepG2 and A549 cells, and thus the arachidonic acid and leukotriene B(4) omega-hydroxylation activities in the nuclear envelope fractions of HepG2 and A549 cells are likely due to cytochrome P450 4F2.