Fatal Intratumoral Hemorrhage Immediately after Gamma Knife Radiosurgery for Brain Metastases: Case Report

Radiosurgical treatment of brain tumors is sometimes considered to be free from significant acute complications or adverse effects. A rare case of fatal intratumoral hemorrhage immediately after gamma knife radiosurgery (GKR) for brain metastasis is reported. A 46-year-old woman with lung cancer complicated by systemic dissemination experienced an acute episode of headache, speech disturbances, and right-side hemiparesis. She had no history of arterial hypertension or coagulation disorders. CT and MRI disclosed multiple brain metastases. The largest tumor, which was located in the left frontal lobe and caused a significant mass effect, was removed microsurgically without any complications. GKR for nine residual metastases was done on the fourth postoperative day. The marginal dose, which corresponded to the 50% prescription isodose line, constituted 20 Gy. No complications were noticed during frame fixation, treatment itself, or frame removal. Fifteen minutes after the end of the GKR session the patient acutely fell into a deep coma. Urgent CT disclosed a massive hemorrhage in the left cerebellar hemisphere in the vicinity of the radiosurgically treated lesion. The patient died 4 days later and autopsy confirmed the presence of intratumoral hemorrhage. In conclusion, GKR for metastatic brain tumors should not be considered as a risk-free procedure and, while extremely rare, even fatal complications can occur after treatment.

Malignant Progression of Benign Brain Tumors after Gamma Knife Radiosurgery: Is it Really Caused by Irradiation?

Malignant transformation of benign neoplasm after radiosurgery is usually diagnosed based on the initial presence of benign tumor, its exposure to ionizing radiation, elapsed time from radiation exposure to malignant progression, and different histological characteristics or growth rate of the regrowing tumor comparing with those originally treated. Three presented cases fulfilled these diagnostic criteria; however, it seems that progression of the tumors (schwannoma, meningioma, chordoma) resulted from the natural course of the disease, rather than represented side effects of gamma knife radiosurgery. Evaluation of the proliferative potential of the benign neoplasm before radiosurgical treatment either directly, if tumor sampling is available, or indirectly, by calculation of the tumor growth rate and/or analysis of the data of the metabolic imaging (PET, MRS) is important for identification of "aggressive" subtypes, precise prediction of prognosis, and confirmation of the radiation-induced malignant transformation in cases of tumor regrowth.

Differentiation of the Radiation-Induced Necrosis and Tumor Recurrence after Gamma Knife Radiosurgery for Brain Metastases: Importance of Multi-Voxel Proton MRS

Comparative analysis of the diagnostic accuracy of FDG PET, single-voxel, and multi-voxel proton MRS for differentiation between radiation-induced necrosis and tumor recurrence was done in 9 patients with brain metastases treated by gamma knife radiosurgery. In all cases enlargement of the lesion and increase of the perilesional edema were demonstrated by MRI on average 10.6+/-2.6 months after initial treatment. Radiation-induced necrosis was identified in 5 patients (histologically in 2, clinically in 3). In one of these a false positive result of FDG PET was observed, whereas data of proton MRS were always correct. The diagnosis of tumor recurrence was established in 4 patients (histologically in 3, clinically in 1). Among these both FDG PET and single-voxel proton MRS showed false negative results (each method twice), whereas multi-voxel proton MRS always permitted us to establish the correct diagnosis. The present study demonstrates the higher diagnostic accuracy of multi-voxel proton MRS, in comparison with single-voxel proton MRS and FDG PET, for the differentiation of the radiation-induced necrosis and tumor recurrence. Its use is especially important in mixed lesions with co-existence of both post-irradiation changes and viable neoplasm. Monitoring of the treatment response by serial multi-voxel proton MRS seems to be reasonable during follow-up of patients with brain metastases after radiosurgery.

Minimally invasive management of the third ventricle glioma in a patient without hydrocephalus: neurofiberscopic biopsy followed by gamma knife radiosurgery

There is usually concern that ventricular enlargement is necessary for safe neuroendoscopic procedures. However, newly developed models of neurofiberscopes with a small outer diameter can be effectively used even in patients without ventriculomegaly. We present the case of a successful neurofiberscopic biopsy of a third ventricle anaplastic astrocytoma in a previously shunted patient without hydrocephalus. Subsequent gamma knife radiosurgery led to complete disappearance of the tumor. It seems that presence of collapsed ventricles, and even symptoms consistent with the slit ventricle syndrome, should not be considered as contraindications for neurofiberscopic surgery when brain compliance is sufficiently preserved. The latter should be considered as the key point of safe endoscopic manipulations. The combination of the neuroendoscopy and stereotactic radiosurgery provides wide possibilities for minimally invasive management of selected intracranial tumors.

Identification of an alternative form of caspase-9 in human gastric cancer cell lines: a role of a caspase-9 variant in apoptosis resistance

Overcoming apoptosis resistance to chemotherapy and radiation may lead to a reduction in gastric cancer death. We hypothesize that the apoptotic machinery in gastric cancer cells is dependent upon specific cellular conditions. In the course of our study of the expression of apoptosis-related genes in human gastric cancer cell lines, we have identified a cDNA clone which predicts an alternative form of caspase-9. The caspase-9 variant, which we designated as caspase-9 beta, retained a truncated structure of native caspase-9 without its catalytic domain and was expressed in seven cell lines from human gastric cancer. Among the cell lines examined, MKN-28 cells, which exhibited the most resistance against apoptotic stimuli, expressed the highest level of caspase-9 beta. The induction of apoptosis by staurosporine or actinomycin D was markedly suppressed in caspase-9 beta-transfected HeLa cells. These results are consistent with our hypothesis that the caspase-9 beta may be an endogenous dominant-negative molecule which attenuates apoptotic activity in human gastric cancer cells.

Pyloricidins, novel anti-Helicobacter pylori antibiotics produced by bacillus sp. II. Isolation and structure elucidation

Novel anti-Helicobacter pylori antibiotics, pyloricidins A, A1, A2, B, C and D were isolated from Bacillus sp. HC-70 and Bacillus sp. HC-72 by column chromatographies using adsorption and ion exchange resins. Their structures have been elucidated based on spectroscopic and degradation studies and shown to be peptide-like compounds. These compounds contained two unusual amino acids, viz., 5-amino-2,3,4,6-tetrahydroxyhexanoic acid and 3-amino-3-phenylpropionic acid (beta-phenylalanine). The structure-activity relationship studies suggested that 3-(5-amino-2,3,4,6-tetrahydroxyhexanoyl)amino-3-phenylpropionic acid moiety was essential for anti-H. pylori activity.

Removal of polyA tails from full-length cDNA libraries for high-efficiency sequencing

We have developed a method to overcome sequencing problems caused by the presence of homopolymer stretches, such as polyA/T, in cDNA libraries. PolyA tails are shortened by cleaving before cDNA cloning with type IIS restriction enzymes, such as GsuI, placed next to the oligo-dT used to prime the polyA tails of mRNAs. We constructed four rice Cap-Trapper-selected, full-length normalized cDNA libraries, of which the average residual polyA tail was 4 bases or shorter in most of the clones analyzed Because of the removal of homopolymeric stretches, libraries prepared with this method can be used for direct sequencing and transcriptional sequencing without the slippage observed for libraries prepared with currently available methods, thus improving sequencing accuracy, operations, and throughput.

Down-regulation of protein kinase C activity by sorbitol rapidly induces apoptosis in human gastric cancer cell lines

Although apoptosis-dependent involution of malignant tumors is associated with a number of non-surgical treatments including chemotherapy, most solid tumors, including gastric cancers, respond poorly to these therapies. In the hope of overcoming the resistance mechanism against non-surgical therapies, we studied the apoptosis-resistance mechanism in cells of gastric cancers as a model system. During the course of our study on apoptotic machinery in human gastric cancer cell lines, we previously found a rapid and efficient induction of apoptosis by sorbitol. In the present study, we demonstrated that the down-regulation of PKC activity in response to sorbitol is a major factor in the induction of apoptotic cell death in gastric cancer cells.

Reference values and limited serological survey for the Iriomote cat in Japan

Clinical investigations and hematological, serum biochemical, and serological surveys were carried out on 11 male and 6 female Iriomote cats (Felis iriomotensis) in Japan. Examined Iriomote cats were considered clinically healthy by the inspection for the general physical conditions. However, urinalysis suggested the inflammation of the urinary tract in all the cats. Antibody for feline panleukopenia virus was positive in one of the examined Iriomote cats, which suggested a previous infection.

Castration-induced expression of caspase-1 in epithelia of accessory sex organs in male rats

AIM

As an attempt to clarify the molecular basis of castration-induced apoptosis, this study was undertaken to demonstrate the expression of caspase-1 in male accessory sex organs of rats.

METHODS AND RESULTS

cDNA of rat caspase-1 was cloned by reverse transcription-polymerase chain reaction from the ventral prostates. The open reading frame predicts 402 amino acids, which shows more than 91% and 63% identity to those of mouse and human, respectively. Northern analyses demonstrated the presence of castration-induced up-regulation of the 1.6 kb transcript in the ventral prostate and the seminal vesicles. Finally, the authors demonstrated the caspase-1 transcripts in the epithelia of these tissues by in situ hybridization analyses.

CONCLUSION

Castration induces the expression of caspase-1 transcripts in the epithelia of ventral prostate and seminal vesicle. These observations suggest a possible role of caspase-1 in apoptosis in male accessory sex organs.

Modulation of MUC1 mucin as an escape mechanism of breast cancer cells from autologous cytotoxic T-lymphocytes

MUC1 mucin is known to serve as a target molecule in the killing of breast cancer cells by cytotoxic T-lymphocytes (CTLs). We searched for a possible mechanism allowing tumour cells to escape from autologous CTLs. When the killing of breast cancer cells by autologous lymphocytes was examined in 26 patients with breast cancer, significant tumour cell lysis was observed in 8 patients, whereas virtually no autologous tumour cell lysis was detected in as many as 18 patients. In the patients who showed negligible tumour cell lysis, the autologous tumour cells expressed MUC1-related antigenic epitopes much more weakly than the tumour cells in the patients who exhibited strong cytotoxicity (significant statistically at P< 0.0005-0.0045), suggesting that the unresponsiveness of cancer cells to CTLs observed in these patients was mainly due to loss of MUC1 expression or modulation of its antigenicity. A breast cancer cell line, NZK-1, established from one of the cytotoxicity-negative patients, did not express MUC1 and was resistant to killing by CTLs, while control breast cancer cell lines expressing MUC-1 were readily killed by CTLs. Transfection of NZK-1 cells with MUC1 cDNA induced significant lysis by autologous T-lymphocytes. These results supported the importance of MUC1 mucin in autologous anti-tumour immunity, but suggested that the major escape mechanism of tumour cells from autologous T-lymphocytes is the loss and/or modulation of MUC1 antigenicity on tumour cells, which would limit the effectiveness of possible immunotherapy designed to target the MUC1 mucin.

Functional annotation of a full-length mouse cDNA collection

The RIKEN Mouse Gene Encyclopaedia Project, a systematic approach to determining the full coding potential of the mouse genome, involves collection and sequencing of full-length complementary DNAs and physical mapping of the corresponding genes to the mouse genome. We organized an international functional annotation meeting (FANTOM) to annotate the first 21,076 cDNAs to be analysed in this project. Here we describe the first RIKEN clone collection, which is one of the largest described for any organism. Analysis of these cDNAs extends known gene families and identifies new ones.

Regulation of mouse kidney tubular epithelial cell-specific expression of core 2 GlcNAc transferase

A mouse gene, Gsl5, controls the expression of Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-6(Galbeta1-3)Gb4Cer and its precursor glycolipids in the kidney by regulating transcription of beta-1,6-GlcNAc transferase. Here we report that Gsl5 controls the expression of the core 2 structure [GlcNAcbeta1-6(Galbeta1-3)GalNAcalpha1-Ser/Thr] of glycoproteins as well as the glycolipid, GlcNAcbeta1-6(Galbeta1-3)GalNAcbeta1-3Galalpha1-4Galbeta1-4Glcbeta1-ceramide. Immunohistochemical studies using an anti-(core 2-Lex) monoclonal antibody demonstrated that lysosome-like vesicles of proximal tubule cells were clearly stained in a Gsl5 wild type mouse, but not in a Gsl5 mutant strain of mice. Western blotting of microsomal fractions of kidney tissue with the same antibody confirmed the histological findings. In situ hybridization with an antisense probe to the kidney-specific mRNA demonstrated that the mRNA is localized at proximal tubule-cells in the cortex adjacent to the medulla, but not detected in glomeruli nor in collecting duct cells in the medulla. The results obtained by immunohistological staining and in situ hybridyzation are compatible and lead to the conclusion that the kidney specific mRNA is expressed in a proximal tubular cell specific manner and produces core 2 GlcNAc transferase responsible for the production of glycoproteins localized at vesicles in the proximal tubular cells. Glycosylation regulated by Gsl5 gene may modify functions of membrane glycoproteins in proximal tubular cells.

Prodromal signs and clinical factors influencing outcome in patients with intraventricular rupture of purulent brain abscess

OBJECTIVE

To elucidate prodromal signs and clinical factors influencing the prognosis in patients with intraventricular rupture of brain abscess (IVROBA) to prevent and manage this catastrophic condition.

METHODS

In this study, 33 consecutive patients with IVROBA diagnosed by computed tomography (CT) were treated. Basic and therapeutic parameters were evaluated as independent predictive factors of a poor prognosis by using univariate analysis. The factors were statistically analyzed based on the interval between initial symptoms and IVROBA.

RESULTS

Patients with a good outcome were younger (<21 yr old) (P < 0.003) and had fewer complications after IVROBA (P < 0.03). For the most part, these patients had undergone aspiration for brain abscess with ventricular drainage combined with the immediate administration of appropriate intravenous and intrathecal antibiotics (P < 0.02). In just a short time, abscesses located in the parieto-occipital region ruptured into the ventricle (P < 0.004), and those with nonsterile cultures (P < 0.01) developed into IVROBA. Just before IVROBA, patients had severe headaches, signs of meningeal irritation, and a rapidly deteriorating clinical condition within 10 days after the signs of meningeal irritation developed. A CT scan obtained before IVROBA ascertained localized enhancement of the ventricular wall adjacent to the abscess.

CONCLUSION

Our findings suggest that signs of meningeal irritation and localized enhancement of the ventricular wall adjacent to the abscess, as observed on CT scans, preceded IVROBA. To decrease the mortality rate associated with purulent brain abscesses, signs forewarning of IVROBA should be recognized, and aggressive management of IVROBA should be initiated. Aggressive CT-guided aspiration of deep-seated abscesses, particularly in the parieto-occipital region, at the time forewarning signs of IVROBA are observed lead to the prevention of IVROBA and an improvement in outcome.

[The efficacy and safety of the nicardipine prolonged-release implant in a canine double hemorrhage model]

A drug delivery system using copoly (lactic/glycol acid) was tested to determine its efficacy and safety in preventing cerebral vasospasm following subarachnoid hemorrhage in dogs. Rod shaped implants (1 mm diameter, 10 mm length, and approximately 10% of nicardipine) was prepared by a heat compression method. Ten dogs were assigned to two groups: double hemorrhage group and double hemorrhage group treated with implants. Vertebral angiography and arterial blood injection into the cisterna magna were performed, followed by midline suboccipital craniectomy and laminectomy of the atlas and placement of nicardipine implants in the cisterna magna. On day 2, arterial blood injection into the cisterna magna was repeated (double hemorrhage model). On day 7, vertebral angiography was repeated. The animals were then sacrificed and the brain and blood clot were taken out. All the animals involved in both groups had been clinically well. Though 5 animals of the control group showed severe vasospasm, no vasospasm was observed in 3 animals and only very mild vasospasm in 2 of the nicardipine-treated group. There was a statistically significant difference in diameter between the two groups (0.5 mm vs 1.1 mm, p = 0.009). Histological examination showed no specific changes related to implants. Furthermore, left frontotemporal craniotomy and placement of nicardipine implants in the carotid-optico cistern were preformed in 3 dogs. Neither clinical symptoms related to implants nor specific histological changes were observed (e.g. hypotension, seizure). These results suggested that nicardipine-prolonged release preparation is safe as well as effective for cerebral vasospasm.

Line versus representational bisections in unilateral spatial neglect

OBJECTIVES

To clarify the mechanisms of left unilateral spatial neglect found in the bisection of lines after cueing to the left end point and to determine whether neglect occurs for the mental representation of a line.

METHODS

A new representational bisection task was developed to eliminate the influence of the right segment of the physical line that would attract attention. Eight patients with typical left unilateral spatial neglect underwent line and representational bisection tasks on a computer display with a touch panel. In the line bisection with cueing, they bisected a line after touching the left end point. In the representational bisection, the patients were presented with a line until they touched the left end point. On the blank display, they pointed to the subjective midpoint of the erased line. The performances of the two bisection tasks were compared when the length and position of stimulus lines were varied.

RESULTS

The rightward errors in the representational bisection were greater than or equivalent to those in the line bisection with cueing. The effect of line length in which the errors became greater for the longer lines was equally found in the line bisection with cueing and the representational bisection. This was confirmed in the condition where the right end point was placed at a fixed position and the line length was varied.

CONCLUSIONS

After cueing to the left end point, rightward bisection errors of patients with neglect are not caused by overattention to the right segment of the physical line. Left neglect occurs mainly for the mental representation formed at the time of cueing or seeing the whole extent of a line.

Prevention of cerebral vasospasm by nicardipine prolonged-release implants in dogs

The purpose of this study was to determine the efficacy of nicardipine prolonged-release implants for preventing vasospasm in a canine SAH model in a dose-escalating placebo-controlled blind fashion. Drug-release kinetics of copoly(lactic/glycolic acid) pellet containing nicardipine were evaluated in vitro. In vivo, 18 dogs were randomly assigned to one of three groups, i.e. placebo, low-dose (0.8 mg), or high-dose (8 mg) nicardipine. Angiography was performed, followed by right craniectomy, the induction of subarachnoid hemorrhage, and the placement of the pellets in the Sylvian fissure. On Day 7 and Day 14, the angiography was repeated. In the first four days, 61.9% of the actual nicardipine loaded was released and within 10 days, 96%. The average percent reductions of vessel diameters in the middle cerebral artery on Day 7 were 43%, 14% and 7% in the placebo, low-dose, and high-dose groups, respectively (p = 0.0319). The mean concentration of nicardipine in the clots on Day 14 was 9.7 x 10(-7) mol-1 l-1 and 5.1 x 10(-6) mol-1 l-1 in the low-dose and high-dose group, respectively. This drug delivery system prevented vasospasm in dogs significantly even at low dose, while maintaining an appropriate concentration of nicardipine in the clot adjacent to the arteries.

T7 RNA polymerase activation and improvement of the transcriptional sequencing by polyamines

We examined the possibility to improve the effectiveness of the in vitro transcription system using T7 RNA polymerase by coexistence with organic bases. The effect of the additives was evaluated by measuring the amount of RNA products in comparison with that of the control system (without additive). We found that four commercial bases and a series of ethylated polyamine analogues newly designed were active enhancers in the following activation order, 1,8-bis(ethylamino)octane > 1,8-octanediamine > 1,5-bis(ethylamino)pentane > cadaverine > 1,8-bis(ethylamino)-4-azaoctane > spermidine 1,18-bis(ethylamino)-5,14-diazaoctadecane > agmatine. It was shown that RNA products were corresponding, only in the presence of active enhancers, to the full length size of the template DNA, and that sequencing signals were enhanced by the presence of active enhancers with high fidelity so that the transcriptional sequencing was further refined to be a highly sensitive sequencing method from a small amount of linear dsDNA. These results suggest that T7 RNA polymerase was activated by the specific binding of the polyamine additive to produce RNA transcripts with fidelity to the template DNA. Therefore, it is expected that the transcriptional sequencing in the presence of active enhancers might be a powerful and sensitive method, in place of the prevalent DNA amplification method, for genomic science projects and clinical and practical gene diagnoses.

Rapid induction of apoptosis in human gastric cancer cell lines by sorbitol

Most solid tumors, including gastric cancers, respond poorly to non-surgical treatments which are expected to induce an apoptosis-dependent involution. We hypothesize that the apoptotic machinery in solid tumors is either defective or in a suppressed condition. Overcoming the ineffective induction of apoptosis may improve the responsiveness of solid tumors to non-surgical treatments. Recently, sorbitol, a kind of hexose, has been found to be an effective inducer of apoptosis in HEp-2 cells. Therefore, it is of particular interest to examine the effect of sorbitol-treatment on gastric cancer cells. in the present study, we selected 4 gastric cancer cell lines which have been reported to exhibit different abilities in regard to apoptosis induction, and examined the effect of sorbitol-treatment on apoptosis induction. Within 3 hr after sorbitol-treatment, apoptosis was induced comparably in all cell lines examined. Cell death in MKN-1, MKN-28 or MKN-74 proceeded in a biphasic manner, while cell death in KATO-III was monophasic. The cell death partially depended on caspase activity. Treatments with sorbitol in combination with 12-O-tetradecanoylphorbol-13-acetate (TPA) markedly suppressed the apoptotic cell death, suggesting a role of protein kinase-C-dependent process. To our knowledge, this is the most rapid induction of apoptosis in human gastric cancer cells reported to date.

Gamma Knife radiosurgery for pituitary adenomas

Ninety-two patients with pituitary adenomas have been treated during the last 5 years. Sixty-three of these patients had more than 6 months follow-up, and they form the basis of this report. Eighteen had non-functioning adenomas (NFA), and 36 had functioning adenomas (FA). The mean marginal dose was 22.5 Gy (NFA 19.5 Gy, FA 23.9 Gy). Control of tumor growth was achieved in 92%. A significant decrease of excessive hormone production was seen in 75.6%, and the endocrinopathy normalization rate was 26.7%. Post-radiosurgical complications were seen in 4.7%.

Low-dose radiosurgery for meningiomas

Gamma Knife radiosurgery is an effective treatment for meningiomas. However, it may be difficult to deliver what is currently considered an optimal dose, especially if the tumor is large or adjacent to critical structures. Eleven cases are presented with a follow-up of more than 12 months where the margin dose did not exceed 10 Gy. The mean age was 48.8 years. The mean follow-up period was 35.7 months (range 21 to 57 months). The mean volume of the tumors was 9.4 cm3 (range 1.6 to 28.9 cm3). The margin dose was less than 10 Gy in all 11 cases, due to a large volume in two cases. Four tumors were close to the visual pathways. Five tumors were close to the brain stem. Imaging follow-up showed that four tumors had shrunk after radiosurgery. The remaining seven cases remained unchanged. There was no tumor growth after radiosurgery. A transient oculomotor palsy was observed in two cases after radiosurgery. It is suggested that Gamma Knife radiosurgery using lower dosage than usual is one of the options for the treatment of meningioma.

Expression of sialyl 6-sulfo Lewis X is inversely correlated with conventional sialyl Lewis X expression in human colorectal cancer

Sialyl 6-sulfo Lewis X determinant has been described recently as a major ligand for L-selectin on high endothelial venules of human peripheral lymph nodes. From our investigation of its distribution in human colorectal cancer tissues and cultured colon cancer cells, the sialyl 6-sulfo Lewis X determinant was preferentially expressed in the nonmalignant colonic epithelia rather than cancer cells (P < 0.001; n = 23). This was in contrast to the distribution of conventional sialyl Lewis X, which was preferentially expressed in cancer tissues rather than nonmalignant epithelia (P = 0.007; n = 23), indicating that 6-sulfation predominantly occurs in nonmalignant tissues and is suppressed upon malignant transformation. In confirmation of this, a nonsialylated determinant 6-sulfo Lewis X was also found to be preferentially localized in the nonmalignant epithelia. Significant expression of sialyl 6-sulfo Lewis X was observed in only 2 lines, whereas 8 were positive for conventional sialyl Lewis X, among 13 cultured colon cancer cell lines. Transfection of cells with fucosyltransferase (Fuc-T) VI induced expression of sialyl 6-sulfo Lewis X, whereas transfection of Fuc-T III did not, suggesting that the determinant was synthesized mainly by Fuc-T VI in colonic epithelia. Members of the sialic acid cyclase pathway, the de-N-acetyl sialyl 6-sulfo Lewis X and cyclic sialyl 6-sulfo Lewis X determinants, were also preferentially expressed in the nonmalignant epithelia rather than colonic cancer cells (P < 0.001; n = 23). Stimulation of the sialyl 6-sulfo Lewis X-positive colon cancer cell line with a calcium ionophore ionomycin markedly reduced sialyl 6-sulfo Lewis X and induced cyclic sialyl 6-sulfo Lewis X expression. These results suggested that the metabolic conversion of sialyl 6-sulfo Lewis X into cyclic sialyl 6-sulfo Lewis X by a calcium-dependent enzyme, sialic acid cyclase, as we hypothesized for human leukocytes previously (C. Mitsuoka et al., Proc. Natl. Acad. Sci. USA, 96: 1597-1602, 1999), also occurs in nonmalignant colonic epithelia.