Helicobacter cinaedi bacteremia in four renal transplant patients: clinical features and an important suggestion regarding the route of infection.

Helicobacter cinaedi can cause bacteremia mainly in immunocompromised patients. We present the clinical characteristics of H. cinaedi bacteremia in 4 renal transplant patients. Interestingly, all cases showed triggers of bacterial translocation: 2 cases developed after colonic perforation caused by diverticulitis, 1 case developed post cholecystectomy, and the remaining patient had chronic diarrhea. Accordingly, bacterial translocation caused by severe gastrointestinal complication could be a cause of H. cinaedi bacteremia.

Once-weekly teriparatide in hemodialysis patients with hypoparathyroidism and low bone mass: a prospective study.

UNLABELLED: Once-weekly 56.5-µg teriparatide treatment was significantly associated with the increase in lumbar spine bone mineral density at 48 weeks among hemodialysis patients with hypoparathyroidism and low bone mass; however, discontinuation of treatment because of adverse events was frequently observed. Careful monitoring for adverse events should be required. INTRODUCTION: Once-weekly 56.5-µg teriparatide is reportedly effective for treating osteoporotic patients without renal insufficiency. However, little is known about the efficacy and safety of once-weekly teriparatide in hemodialysis patients. METHODS: We conducted a 48-week prospective, observational cohort study including 22 hemodialysis patients aged 20 years or older with hypoparathyroidism and low bone mass who received once-weekly teriparatide at 56.5 µg at a tertiary care hospital between January 2013 and January 2015. Primary outcomes were within-subject percent changes of bone mineral density (BMD) at the lumbar spine, femoral neck, and distal one-third radius at 24 and 48 weeks. Secondary outcomes included percent changes of serum bone turnover markers (osteocalcin, bone-specific alkaline phosphatase (BAP), N-terminal propeptide of procollagen type 1 (P1NP), and tartrate-resistant acid phosphatase 5b (TRAP-5b)). Adverse events were evaluated. RESULTS: The BMD increased at the lumbar spine by 3.3 ± 1.9 % (mean ± SEM) and 3.0 ± 1.8 % at 24 and 48 weeks but not in the femoral neck and distal one-third radius. Serum osteocalcin, BAP, and P1NP increased significantly at 4 weeks, maintaining higher concentrations up to 48 weeks, although TRAP-5b decreased gradually during treatment. The baseline BAP was significantly associated with the 48-week percent change in lumbar spine BMD. Transient hypotension was the most common adverse event. Ten patients discontinued treatment because of adverse events. CONCLUSIONS: Once-weekly teriparatide was associated with increased lumbar spine BMD in hemodialysis patients with hypoparathyroidism and low bone mass. Careful monitoring should be required for treatment of such patients.

Colovesical Fistula After Renal Transplantation: Case Report.

Colovesical fistula is a relatively rare condition that is primarily related to diverticular disease. There are few reports of colovesical fistula after renal transplantation. We report of a 53-year-old man who was diagnosed with colovesical fistula after recurrent urinary tract infection, 5 months after undergoing cadaveric renal transplantation. Laparoscopic partial resection of the sigmoid colon with the use of the Hartmann procedure was performed. Six months after that surgery, there was no evidence of recurrent urinary tract infection and the patient's renal graft function was preserved. Physicians should keep colovesical fistula in mind as a cause of recurrent urinary tract infection in renal transplant recipients, especially in those with a history of diverticular disease.

Cyst infection in autosomal dominant polycystic kidney disease: causative microorganisms and susceptibility to lipid-soluble antibiotics.

Cyst infection is a frequent and serious complication of autosomal dominant polycystic kidney disease (ADPKD). Lipid-soluble antibiotics like fluoroquinolones show good penetration into cysts and are recommended for cyst infection, but causative microorganisms are often resistant to these agents. This study investigated the profile of the microorganisms causing cyst infection in ADPKD, their susceptibility to lipid-soluble antibiotics, and clinical outcomes. This retrospective study reviewed all ADPKD patients admitted to Toranomon Hospital with a diagnosis of cyst infection from January 2004 to March 2014. All patients who underwent cyst drainage and had positive cyst fluid cultures were enrolled. Patients with positive blood cultures who satisfied our criteria for cyst infection or probable infection were also enrolled. There were 99 episodes with positive cyst fluid cultures and 93 episodes with positive blood cultures. The majority of patients were on dialysis. The death rate was high when infection was caused by multiple microorganisms or when there were multiple infected cysts. Gram-negative bacteria accounted for 74-79 % of the isolates in all groups, except for patients with positive hepatic cyst fluid cultures. The susceptibility of Escherichia coli to fluoroquinolones was very low in patients with hepatic cyst infection, especially those with frequent episodes and those with hepatomegaly. Fungi were detected in two episodes. Fluoroquinolone-resistant microorganisms showed a high prevalence in cyst infection. It is important to identify causative microorganisms to avoid the overuse of fluoroquinolones and to improve the outcome of cyst infection in ADPKD.

Impact of tubulointerstitial lesions on anaemia in patients with biopsy-proven diabetic nephropathy.

AIMS: To investigate the relationship between the progression of anaemia and renal pathological findings in patients with diabetic nephropathy. METHODS: A total of 223 patients with diabetes underwent renal biopsy from 1985 to 2010 and were confirmed to have pure diabetic nephropathy according to the recent classification, of whom 113 (baseline haemoglobin ≥ 11 g/dl) were enrolled in the study. Linear regression analysis was used to estimate the changes in haemoglobin levels during the follow-up period. RESULTS: In a multivariate model adjusted for clinical and histopathological variables, higher interstitial fibrosis and tubular atrophy scores were more strongly associated with a decrease in haemoglobin levels than were lower scores. Compared with an interstitial fibrosis and tubular atrophy score of 0, the standardized coefficients for interstitial fibrosis and tubular atrophy scores of 1, 2 and 3 were 0.20 (95% CI -0.31 to 0.93), 0.34 (95% CI -0.22 to 1.34) and 0.47 (95% CI 0.07 to 1.96), respectively, whereas a higher glomerular class, a higher vascular lesion score and the presence of exudative lesions were not strongly correlated with the decrease in haemoglobin. CONCLUSIONS: Tubulointerstitial lesions that are more advanced are significantly associated with the progression of anaemia in patients with diabetic nephropathy after adjustment for numerous covariates. This finding suggests that tubulointerstitial lesions may be a useful prognostic indicator for anaemia in patients with diabetic nephropathy, and that decreased erythropoietin production attributable to the progression of tubulointerstitial lesions is a major cause of anaemia in these patients.

Bone histomorphometry in a long-term hemodialysis patient with hypoparathyroidism and sarcoidosis.

A bone biopsy specimen in a long-term hemodialysis patient with sarcoidosis coexisting with severe hypoparathyroidism has demonstrated that a persistent near physiological level of 1,25-dihydroxyvitamin D3 contributes to the preservation of bone remodeling and has the potential to retard the development of vascular calcification and atherosclerosis. Sarcoidosis-related hypercalcemia and hypoparathyroidism, which is characterized by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) overproduction, is rarely seen in hemodialysis patients. Herein, we describe a 60-year-old Japanese woman on hemodialysis for 35 years who presented with malaise and hypercalcemia. Severe hypoparathyroidism without parathyroidectomy and a preserved 1,25(OH)2D3 level were detected. Computed tomography showed bilateral axillary lymphadenopathy and minimal aortic and soft tissue calcification. The axillary node biopsy led to a definite diagnosis of sarcoidosis. A bone biopsy specimen obtained from the right iliac crest showed remodeling of normal lamellar bone with scalloped cement lines and clear double labeling by tetracycline on fluorescence microscopy. Histomorphometric analysis revealed that the bone formation rate was preserved (30.0 %/year), together with a decrease of osteoid volume (5.75 %) and fibrous volume (0 %), indicating that the patient did not have adynamic bone disease and only showed mild disease. This is the first documented case of sarcoidosis-related hypercalcemia associated with severe hypoparathyroidism in a long-term hemodialysis patient who underwent bone histomorphometry. Our findings suggest that, in hemodialysis patients with sarcoidosis coexisting with severe hypoparathyroidism, a persistent near physiological level of 1,25(OH)2D3 contributes to the preservation of bone remodeling and has the potential to retard the development of vascular calcification and atherosclerosis.

Long-term complete remission of multiple extranodal natural killer/T-cell-type posttransplant lymphoproliferative disorder after surgical resection: a case report.

BACKGROUND: Posttransplant lymphoproliferative disorder (PTLD) is a life-threatening complication of organ transplantation that results from immunosuppression therapy. Most cases of PTLD derive from the B-cell lineage. T-cell PTLD, particularly natural killer (NK)/T-cell PTLD, is quite rare; only a few cases have been described. CASE REPORT: A 42-year-old woman received a living-related renal allograft from her father. Sixteen years after transplantation, the patient presented with a 1-week history of low-grade fever and epigastralgia. Computed tomography revealed intestinal masses and a right upper lung lobe mass. Gallium scintigraphy showed uptake in the abdominal mass. Epstein-Barr virus-related antibody was not detected in the patient's serum sample. We performed extirpation of the jejunum and ileum tumors. The pathologic findings showed that these 2 tumors were NK/T-cell lymphoma. After the operation, the lung mass rapidly enlarged, and right upper lobectomy was performed. The right upper lung lobe tumor showed the same histopathologic findings as the small bowel tumor. The final histologic diagnosis was established as multiple extranodal NK/T cell type PTLD of the small bowel and right upper lung lobe. CONCLUSIONS: After reduction of the immunosuppressive agent, no recurrence of PTLD has been observed for the past 9 years.

Identification and characterization of novel multiple bacteriocins produced by Lactobacillus sakei D98.

AIM: To characterize novel multiple bacteriocins produced by Lactobacillus sakei D98. METHODS AND RESULTS: Lactobacillus sakei D98 isolated from Shubo (rice malt) produced at least three bacteriocins. Using three purification steps, three novel antimicrobial peptides termed sakacin D98a, sakacin D98b and sakacin D98c were purified from the culture supernatant. Amino acid and DNA sequencing analysis revealed that the sakacins D98a, D98b and D98c are novel class IIa-like or class IId bacteriocins. In particular, sakacin D98b has a variant pediocin-box sequence, YANGVXC (with Ala instead of Gly), and a different location for the disulfide bridge (Cys(11) and Cys(18)) from that found in other class IIa bacteriocins. CONCLUSIONS: Three novel bacteriocins were identified from Lactobacillus sakei D98. Their antimicrobial spectra and intensities indicate that these sakacins would have different modes of action. In addition, sakacin D98b showed low inhibitory activity against Listeria, probably due to the differences in amino acids and position of the disulfide bridge compared with the other class IIa bacteriocins. SIGNIFICANCE AND IMPACT OF STUDY: Sakacins D98a and D98c are novel bacteriocins belonging to class IId bacteriocins. On the other hand, sakacin D98b, a class IIa-like bacteriocin, has a unique internal structure and activity spectrum.

Characterization and identification of weissellicin Y and weissellicin M, novel bacteriocins produced by Weissella hellenica QU 13.

AIMS: To identify and characterize novel bacteriocins from Weissella hellenica QU 13. METHODS AND RESULTS: Weissella hellenica QU 13, isolated from a barrel used to make Japanese pickles, produced two novel bacteriocins termed weissellicin Y and weissellicin M. The primary structures of weissellicins Y and M were determined, and their molecular masses were determined to be 4925·12 and 4968·40 Da, respectively. Analysis of the DNA sequence encoding the bacteriocins revealed that they were synthesized and secreted without N-terminal extensions such as leader sequences or sec signal peptides. Weissellicin M showed significantly high and characteristic homology with enterocins L50A and L50B, produced by Enterococcus faecium L50, while weissellicin Y showed no homology with any other known bacteriocins. Both bacteriocins showed broad antimicrobial spectra, with especially high antimicrobial activity against species, which contaminate pickles, such as Bacillus coagulans, and weissellicin M showed relatively higher activity than weissellicin Y. Furthermore, the stability of weissellicin M against pH and heat was distinctively higher than that of weissellicin Y. CONCLUSIONS: Weissella hellenica QU 13 produced two novel leaderless bacteriocins, weissellicin Y and weissellicin M, and weissellicin M exhibited remarkable potency that could be employed by pickle-producing industry. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first report, which represents a complete identification and characterization of novel leaderless bacteriocins from Weissella genus.

A case of familial lecithin-cholesterol acyltransferase deficiency on hemodialysis for over 20 years.

We trace the 34-year history of a member of the first Japanese family in which lecithin-cholesterol acyltransferase (LCAT) deficiency was diagnosed. Marriage between cousins with low LCAT activity was responsible for familial LCAT deficiency (FLD). In 1976, a 27-year-old Japanese man was noted to have FLD based on proteinuria, hematuria, grayish corneal opacity and low LCAT activity (9.83%). Genetic analysis showed insertion of G-G-C coding glycine at codon 141. Total cholesterol (C) was low at 108 mg/dl and the ratio of C-ester to total C was very low (12%), while the lecithin (phosphatidylcholine) level was very high (97.3%). When his serum creatinine reached 2.6 mg/dl at the age of 41 years (in 1991), renal biopsy was performed. This showed expansion of the mesangial matrix and irregularly thickened capillary walls with a bubble-like appearance because of lipid deposits consisting of two components (partly lucent vacuolated areas and partly deeply osmiophilic areas). Magnification of the latter deposits showed curvilinear and serpiginous striated membranous structure. Hemodialysis was started in 1990 and has been continued for over 20 years until August 2010. Clinical problems have included AV shunt failure requiring 4 operations and 13 percutaneous transcatheter angioplasty procedures, as well as episodes of hemolytic anemia that subsided after infusion of fresh frozen plasma. Cardiovascular events have not yet occurred, although severe calcification of abdominal aorta has been detected by computed tomography.

Hepatitis C virus-related kidney disease: various histological patterns.

BACKGROUND: Although hepatitis C virus (HCV) infection is known to be associated with Type 2 cryoglobulinemic glomerulopathy (CG), only a few reports about other types of nephropathy have been published. METHODS: 68 HCV antibody positive patients in whom renal biopsy had been performed for persistent proteinuria, hematuria, and/or renal dysfunction between 1992 and 2008 at our institute were included. The histological, clinical and laboratory characteristics including the age, gender, hypertension, diabetes mellitus, liver histology (chronic hepatitis or liver cirrhosis), HCV-RNA, HCV genotype, splenomegaly, gastroesophageal varices, serum creatinine, hemoglobin, platelet count, rheumatoid factor, cryoglobulin, IgG, IgA, IgM, CH50, C3, C4, creatinine clearance, 24-h protein excretion, and hematuria, between their nephropathy with and without immune deposition were compared. RESULTS: Nephropathy was classified into two groups based on the detection of immune deposits by immunofluorescence microscopy: i.e., a positive group (n = 39) and a negative group (n = 29). The former group was further classified into three types of nephropathy: IgG dominant group (n = 10) (including membranous nephropathy (MN)), IgA dominant group (n = 20) (including IgA nephropathy (IgAN)), membranoproliferative glomerulonephritis (MPGN) (IgA type)), and IgM dominant group (n = 9) (MPGN apart from the IgA type). The latter group included diabetic nephropathy (n = 13), focal glomerular sclerosis (n = 4), and benign nephrosclerosis (n = 3), malignant nephrosclerosis (n = 1), tubulointerstitial nephritis (TIN) (n = 2), minimal change nephrotic syndrome (n = 1), cast nephropathy (n = 1), granulomatous TIN (n = 1), and others (n = 3). An increased serum IgM level, hypocomplementemia, splenomegaly, thrombocytopenia, liver cirrhosis, hematuria, and a high HCV RNA level were features of patients with MPGN of IgM dominant group (consistent with "CG"). CONCLUSIONS: Our results showed various histological patterns of HCV-related kidney disease and the specificity of CG, and revealed that a minority of HCV patients (n = 7) presented typical CG, while IgAN, MN, and diabetic nephropathy were more frequent.

Identification and characterization of novel multiple bacteriocins produced by Leuconostoc pseudomesenteroides QU 15.

AIM: To characterize novel multiple bacteriocins produced by Leuconostoc pseudomesenteroides QU 15. METHODS AND RESULTS: Leuconostoc pseudomesenteroides QU 15 isolated from Nukadoko (rice bran bed) produced novel bacteriocins. By using three purification steps, four antimicrobial peptides termed leucocin A (ΔC7), leucocin A-QU 15, leucocin Q and leucocin N were purified from the culture supernatant. The amino acid sequences of leucocin A (ΔC7) and leucocin A-QU 15 were identical to that of leucocin A-UAL 187 belonging to class IIa bacteriocins, but leucocin A (ΔC7) was deficient in seven C-terminal residues. Leucocin Q and leucocin N are novel class IId bacteriocins. Moreover, the DNA sequences encoding three bacteriocins, leucocin A-QU 15, leucocin Q and leucocin N were obtained. CONCLUSIONS: These bacteriocins including two novel bacteriocins were identified from Leuc. pseudomesenteroides QU 15. They showed similar antimicrobial spectra, but their intensities differed. The C-terminal region of leucocin A-QU 15 was important for its antimicrobial activity. Leucocins Q and N were encoded by adjacent open reading frames (ORFs) in the same operon, but leucocin A-QU 15 was not. SIGNIFICANCE AND IMPACT OF STUDY: These leucocins were produced concomitantly by the same strain. Although the two novel bacteriocins were encoded by adjacent ORFs, a characteristic of class IIb bacteriocins, they did not show synergistic activity.

The long-term survival rate of catecholamine-resistant septic shock in Japanese patients who received vasopressin therapy.

BACKGROUND: Septic shock is associated with vasopressin deficiency and hypersensitivity to its exogenous administration. The aim of this study is to review the 28-day survival rate, hemodynamic and renal effects of vasopressin therapy in refractory septic shock Japanese patients. METHODS: 55 Japanese patients experiencing catecholamine-resistant septic shock were treated with vasopressin. Hemodynamic alterations and the serum concentrations of aspartate aminotransferase, total bilirubin and creatinine clearance were evaluated following vasopressin treatment. RESULTS: In both, survivors and non-surviving patients, treatment with vasopressin resulted in a significantly increase in mean arterial pressure, hourly urine output, and a significant decrease in heart rate and total pressor dosage requirements. Creatinine clearance was significantly increased only in survivors. There were no significant changes in the serum concentrations of aspartate aminotransferase and total bilirubin. The 28-day survival rate was 45% (25 patients). CONCLUSIONS: In Japanese septic shock patients, vasopressin infusion improved hemodynamic status and reduced catecholamine requirement, and 28-day survival rate was 45%.

A patient with pregnancy-related acute abdomen after hemodialysis for over 18 years.

Because pregnancy is rare in women with end-stage renal disease, dialysis patients have not been reported to present with acute abdominal symptoms related to pregnancy including ectopic pregnancy. A 41-year-old woman treated with hemodialysis for over 18 years was brought to the emergency room at our institution because of acute abdominal pain. Ultrasonography detected an abdominal fluid collection, and her anemia had worsened (hematocrit 18%). Emergency laparoscopic exploration disclosed a hemorrhagic corpus luteum of pregnancy, causing ovarian bleeding on the left. Coagulation of bleeding points was carried out. At this time, pregnancy at 7 weeks of gestation was discovered. After the procedures, hemodialysis frequency was increased to 5 times weekly, and an erythropoietin derivative was administered to maintain a hematocrit above 30%. The patient developed no hypertension. At 33 weeks of gestation, cesarean section was performed because of a decrease in amniotic fluid and frequent late deceleration of the fetal heart rate. A live baby girl weighing 1,422 g was born. The successful pregnancy reflects remarkable progress in dialysis technology. Pregnancy, then, can underlie an acute abdomen in childbearing-age women (14 - 44 years old) undergoing long-term dialysis.

Multicentric Castleman disease with secondary AA renal amyloidosis, nephrotic syndrome and chronic renal failure, remission after high-dose melphalan and autologous stem cell transplantation.

Multicentric Castleman disease is a systemic lymphoproliferative disease with incomplete understood etiology. The various renal complications of this disease may include minimal change disease, mesangial proliferative glomerulonephritis, membranous glomerulonephritis and nephrotic syndrome, caused by secondary amyloidosis. In several reported cases of localized Castleman disease associated with renal amyloidosis and nephrotic syndrome, resection of organs involved by lymphoid proliferation resulted in complete remission. However, therapy of multicentric Castleman disease with renal amyloidosis is not well-established. We treated a case of a 39-year-old woman with multicentric Castleman disease complicated by nephrotic syndrome caused by secondary AA amyloidosis. The patient underwent autologous peripheral blood stem cell transplantation (auto-PBSCT), achieving complete remission. Autologous stem cell transplantation may be an attractive choice in therapy for refractory multicentric Castleman disease.

A pediatric occurrence of crescentic glomerulonephritis associated with antineutrophil cytoplasmic antibodies and mesangial IgA deposits.

Antineutrophil cytoplasmic antibody-(ANCA) associated glomerulonephritis usually shows histopathologic features of pauciimmune crescentic glomerulonephritis and occurs late in life. We report a 14-year-old Japanese girl presenting with proteinuria, hematuria and mildly elevated serum creatinine. A renal biopsy specimen demonstrated crescentic glomerulonephritis, immunofluorescence showed mesangial IgA staining. Electron microscopic examination disclosed paramesangial deposits. Serum ANCA against myeloperoxidase (MPO) were detected at high titers. Myeloperoxidase-ANCA-related nephritis accompanied by IgA nephropathy is considered rare in childhood and teen years. Yet, if ANCA assays and detailed electron microscopic examination of renal specimens were performed routinely in patients with rapidly progressive glomerulonephritis, the diagnosis might be more frequent in young patients.

Ribozyme-mediated inactivation of mutant K-ras oncogene in a colon cancer cell line.

Mutation of c-K-ras oncogene is an important step in progression of colon cancer. We used a hammerhead ribozyme (KrasRz) against mutated K-ras gene transcripts (codon 12, GTT) to inactivate mutant K-ras function in the colon cancer cell line SW480, harbouring a mutant K-ras gene. The beta-actin promoter-driven KrasRz sequence (pHbeta/KrasRz) was introduced into these cells (SW480/KrasRz), and we evaluated its effects on growth of the colon cancer. The gene expression of angiogenesis-related molecules (vascular endothelial growth factor and thrombospondin) was also estimated in SW480/KrasRz. KrasRz specifically and efficiently cleaved the mutant K-ras mRNA but not wild-type mRNA in vitro. SW480/KrasRz showed decreased growth rate under tissue culture conditions (P< 0.01, Dunnett's test). The xenotransplantability of SW480/KrasRz (XeSW480/KrasRz) was significantly decreased in nude mice (P< 0.05, Fisher's exact test). Tumour volume of the xenografts XeSW480/KrasRz was significantly smaller than that of XeSW480/DisKrasRz (P< 0.01, Dunnett's test). Gene expression of VEGF was suppressed in SW480/KrasRz, while TSP1 gene expression was enhanced. The SW480/KrasRz cells showed apoptosis-related features including nuclear condensation and DNA fragmentation. These results suggested that the hammerhead ribozyme-mediated inactivation of the mutated K-ras mRNA induced growth suppression, apoptosis and alteration of angiogenic factor expression.

In vivo chemosensitivity of human malignant cystosarcoma phyllodes xenografts.

Malignant cystosarcoma phyllodes (MCSP) is a rare breast tumor. Chemotherapeutic regimens for treatment of MCSP have not been established. We previously established an MCSP xenograft line MC-3-JCK. In this study, we established a new MCSP xenograft line, MC-10-JCK, by serial transplantation in nude mice. We studied the chemosensitivity of these two MCSP tumor xenografts to anticancer drugs in vivo. We also examined the expression of multidrug resistance-related proteins such as p-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP) by immunohistochemical analysis. These two xenografts were sensitive to doxorubicin, vincristine and cyclophosphamide in vivo. Immunohistochemically, clinical specimens and xenografts were negative for Pgp and MRP expression. These results are consistent with the chemosensitivity of human MCSP to lipophilic anticancer compounds.

Heterozygous ras mutations are preserved in serially passaged human tumor xenografts and established cell lines.

We examined c-K-ras gene point mutations in human tumor xenografts and established cell lines as markers of genetic stability. Our previous study demonstrated the stability of c-K-ras gene mutations in human primary neoplasms and their tumor xenografts through serial passages in mice. In this study, we established 27 human cell lines derived from various human tumor xenografts in nude mice. Point mutation of the c-K-ras gene at codon 12 was found in 29.6% (8/27) of the cell lines, as well as in 29.6% (8/27) of the xenografts. The eight ras-mutated cell lines were derived from corresponding tumor xenografts carrying the ras mutation. Heterozygous ras gene mutation was confirmed in seven of the eight ras-mutated cell lines, as well as their corresponding xenografts. The incidence, type and heterozygosity of the c-K-ras gene mutation showed no discrepancies between the original xenografts and the established cell lines. From these findings, we concluded that point mutation of the c-K-ras gene was very stable in human tumor xenografts and established cell lines derived from the xenografts.