Down-regulation of stimulator of interferon genes (STING) expression and CD8+ T-cell infiltration depending on HER2 heterogeneity in HER2-positive gastric cancer

BACKGROUND

HER2 signaling might be involved in the regulation of immune cell activation in the tumor microenvironment (TME) of gastric cancer (GC). However, the relationship between HER2 status and immune cell condition in the HER2-positive GC TME is not clearly understood.

METHODS

To investigate the effect of HER2 signaling on the activation of the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway, which contributes to immune cell activation in the GC TME, we evaluated the associations among the expressions of HER2, cGAS-STING, and the number of CD8+ tumor-infiltrating lymphocytes (TIL) by considering HER2 heterogeneity in HER2-positive GC tissues. We also examined the effect of HER2 signaling on the activation of STING signaling in vitro using human HER2-positive GC cell lines.

RESULTS

The expression of HER2 is highly heterogeneous in HER2-positive GC tissues, and we found that the number of CD8+ TIL in HER2 high areas was significantly lower than that in HER2 low areas in HER2-positive GC tissues. Intriguingly, the tumor cell-intrinsic expression of STING, but not cGAS, was also significantly lower in the HER2 high areas than the HER2 low areas in HER2-positive GC tissues. Moreover, in vitro experiments, we demonstrated that the blockade of HER2 signaling increased the expression of STING and its target genes, including IFNB1, CXCL9/10/11, and CCL5, in HER2-positive GC cell lines.

CONCLUSIONS

Our results suggest that HER2 signaling might suppress immune cell activation in the GC TME by inhibiting STING signaling in tumor cells in HER2-positive GC.

Functional benefits of the double flap technique after proximal gastrectomy for gastric cancer

BACKGROUND

Proximal gastrectomy is a widely performed procedure that has become more common with an increasing number of proximal gastric cancer cases. Several types of reconstructive procedures after proximal gastrectomy have been developed, and it remains controversial which procedure is the most advantageous with regard to the preservation of postoperative gastric stump function and nutritional status. In the present study, we retrospectively analyzed reconstructive procedures in a consecutive case series for proximal gastrectomy, primarily focusing on postoperative body weight maintenance, nutritional status, and gastric remnant functional preservation.

METHODS

We enrolled 69 patients who had undergone proximal gastrectomy for gastric cancer in our institute between 2005 and 2020. Short-term complications, preservation of gastric remnant functions, nutritional status, and post-operative weight changes were compared.

RESULTS

After proximal gastrectomy, the numbers of patients who underwent direct esophago-gastrostomy, jejunal interposition, double tract reconstruction, and the double flap technique were 9, 10, 14, and 36, respectively. The patients in whom the double flap technique was performed suffered no reflux esophagitis after surgery. Prevalence of gastric residual at 12 months after surgery was lowest in the double flap technique group. Moreover, the double flap technique group had a better tendency regarding post-operative changes of serum albumin ratios. Furthermore, the post-operative body weight change ratio of the double flap technique group was smallest among all groups and was significantly better than that of the double tract group.

CONCLUSIONS

The double flap technique after proximal gastrectomy was considered the most effective technique for reconstruction which leads to better bodyweight maintenance, and results in less reflux esophagitis.

[A Case of Laparoscopic Surgery for Preoperatively Diagnosed Gastric Metastasis of Lung Cancer]

The patient was a 66-year-old male who had undergone an operation for lung cancer and solitary brain metastases. Follow- up PET-CT after 1 year detected FDG accumulation in the stomach. We performed esophagogastroscopy and found an approximately 20 mm-sized Type 2 tumor on the greater curvature of the upper stomach. A pathological diagnosis of lung adenocarcinoma metastasis in the stomach was made. Laparoscopic surgery was performed on the metastatic lesion to prevent bleeding and perforation, and resection was achieved with minimal invasion. The current development of chemotherapy, including immunotherapy, has contributed to the improved prognosis of cancer patients, including those with lung metastasis in the stomach. Considering these backgrounds, preventive surgical resection under laparoscopy may be an effective approach for improving prognosis and preventing acute life-threatening adverse events. We report this case along with a literature review.

ARID1A deficiency in EBV-positive gastric cancer is partially regulated by EBV-encoded miRNAs, but not by DNA promotor hypermethylation

AT-rich interactive domain 1A (ARID1A), which is a tumor suppressor gene, is frequently mutated in Epstein-Barr virus-positive gastric cancer [EBV (+) GC]. While most ARID1A mutations in GC are truncating mutations, leading to loss of ARID1A protein expression, epigenetic modifications appear to contribute to ARID1A deficiency in EBV (+) GC harboring wild-type ARID1A. Based on the significant role of epigenetic modifications in EBV (+) GC that contributes to ARID1A deficiency, the methylation status of ARID1A was evaluated in EBV-infected cells and GC patients using a publicly available microarray and the Cancer Genome Atlas (TCGA) database. EBV-encoded miRNAs that potentially target ARID1A were identified as an additional epigenetic modulator by computational prediction. In vitro experiments were conducted to evaluate how EBV-encoded miRNAs affected ARID1A mRNA and protein levels. In clinical GC samples, the expression of predicted miRNAs and ARID1A and the mutation status of ARID1A was evaluated. As results, ARID1A was not hypermethylated in EBV (+) GC samples or EBV-infected GC cells. EBV infection did not alter ARID1A mRNA levels, suggesting that ARID1A protein deficiency was caused by post-transcriptional gene silencing in ARID1A-WT EBV (+) GC. Overexpression of miR-BART11-3p and miR-BART12, which were identified as miRNAs that potentially bind ARID1A, suppressed ARID1A protein expression in MKN7 and NCI-N87 cells. Highly expressed miR-BART11-3p and miR-BART12 were correlated with decreased ARID1A levels in GC tumors which did not harbor ARID1A mutations. The present findings revealed that ARID1A expression was epigenetically regulated by miR-BART11-3p and miR-BART12 in EBV (+) GC.

Stromal expression of cancer-associated fibroblast-related molecules, versican and lumican, is strongly associated with worse relapse-free and overall survival times in patients with esophageal squamous cell carcinoma

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment play an essential role in the tumor progression of esophageal squamous cell carcinoma (ESCC). The present study aimed to investigate the expression of CAF-related molecules, versican, periostin and lumican, in cancer stroma, to provide prognostic stratification for patients with ESCC after surgery. A total of 106 patients with ESCC who underwent curative esophagectomy without preoperative chemotherapy or radiotherapy were enrolled. The expression of CAF-related stromal proteins, including versican, periostin and lumican, was examined using immunohistochemistry, and the prognostic value was assessed by Kaplan-Meier survival analysis, and univariate and multivariate Cox regression models. The expression of versican, periostin and lumican was found specifically in the stromal component of ESCC. Kaplan-Meier analysis demonstrated that, compared with a low expression level, a high expression level of versican, periostin or lumican in the cancer stroma was significantly associated with worse relapse-free survival (RFS) and overall survival times in patients with ESCC. The prognostic values of stromal versican and lumican remained significant in a stratified analysis of stage I patients. Moreover, univariate and multivariate analysis revealed that high stromal versican or lumican expression was an independent prognostic factor for RFS in the patients. The present study demonstrated that CAF-related molecules, including versican, periostin and lumican, were expressed in the stroma of ESCC, and that stromal expression of versican and lumican in particular may have clinical utility as a prognostic biomarker for poor RFS in postoperative patients with ESCC.

Neoadjuvant Chemotherapy Induces IL34 Signaling and Promotes Chemoresistance via Tumor-Associated Macrophage Polarization in Esophageal Squamous Cell Carcinoma

The tumor microenvironment (TME) plays a key role in the efficacy of neoadjuvant chemotherapy (NAC) in solid tumors including esophageal squamous cell carcinoma (ESCC). However, the TME profile of ESCC treated with NAC is not fully understood. In this study, we investigated the effect of NAC on the TME especially tumor-associated macrophages (TAM), the important immunosuppressive components of the TME, in ESCC. We quantified the expression of CD163, a crucial marker of TAM, in pretherapeutic biopsy and surgically resected ESCC specimens from patients who received NAC (n = 33) or did not receive NAC (n = 12). We found that NAC dramatically increased the expression of CD163 on TAMs in ESCC. Colony-stimulating factor 1 (CSF-1) and IL34 are crucial cytokines that recruit monocytes into tumor sites and differentiate them into TAMs. Interestingly, NAC significantly upregulated the expression of IL34 but not CSF-1 on tumor cells, and the frequencies of CD163⁺ TAMs were significantly correlated with IL34 expression in ESCC after NAC. The expression of IL34 in NAC-nonresponsive patients was significantly higher than that in NAC-responsive patients, and patients with IL34-high ESCC exhibited worse prognosis as compared with patients with IL34-low ESCC. We also demonstrated that 5-fluorouracil (5-FU)/cisplatin preferentially increased mRNA expression of IL34 on human ESCC cell lines. Human peripheral blood monocytes co-cultured with ESCC cells treated with 5-FU/cisplatin increased the expression of CD163, which was attenuated by the treatment with CSF-1R inhibitors. These data suggest that IL34 expression by NAC shifts the TME toward CD163⁺ TAM-rich immunosuppressive and chemo-insensitive microenvironment in ESCC. IMPLICATIONS: The blockade of IL34 signaling may offer a novel therapeutic strategy against chemoresistance in ESCC by inhibiting M2-TAM polarization.

Selective sensitivity of EZH2 inhibitors based on synthetic lethality in ARID1A-deficient gastric cancer

BACKGROUND

AT-rich interactive domain 1A (ARID1A) is a tumor suppressor gene that is frequently mutated in gastric cancer (GC). Although ARID1A mutations are not a druggable target for conventional treatments, novel therapeutic strategies based on a synthetic lethal approach are effective for ARID1A-deficient cancers. The histone methyltransferase EZH2 acts in a synthetic lethal manner in ARID1A-mutated ovarian cancer, although its role in GC remains unknown.

METHODS

The selective sensitivity of the EZH2 inhibitors for ARID1A-deficient GC cells was evaluated using cell viability and colony formation assays. The expression of PI3K/AKT signaling genes were investigated using TCGA's cBioPortal database to determine whether the homeostasis between ARID1A and EZH2 is related to cell proliferation and survival via the PI3K/AKT signaling pathway. We also evaluated the phosphorylation of PI3K/AKT signaling proteins in ARID1A knock downed ARID1A-WT GC cells.

RESULTS

EZH2 inhibitors decreased the viability of ARID1A-deficient cells in a dose-dependent manner and demonstrated the selective sensitivity to ARID1A-deficient cells in vitro experiment system. Bioinformatics approach revealed that the PI3K/AKT signaling was tended to be activated in ARID1A-deficient GC enhancing cell viability and, furthermore, down-regulation of EZH2 in ARID1A-deficient GC was related to normalization of PI3K/AKT signaling pathway. The cell experiment revealed that phosphorylated AKT was upregulated in ARID1A-deficent GC cells.

CONCLUSIONS

The present findings provide a rationale for the selective sensitivity of EZH2 inhibitors against ARID1A-deficient GC and suggest the potential efficacy of targeted therapy using EZH2 inhibitors in this patient population.

Tn Antigen Expression Defines an Immune Cold Subset of Mismatch-Repair Deficient Colorectal Cancer

Colorectal cancer (CRC) cells often express Tn antigen, a tumor-associated truncated immature O-glycan (GalNAcα-O-Ser/Thr) that can promote tumor progression. Immunotherapies against Tn antigen have been developed and are being evaluated in clinical trials. Tn antigen can also be considered a novel immune checkpoint that induces immunosuppressive signaling through glycan-biding lectins to lead effector T cell apoptosis. We evaluated the correlation of Tn antigen expression by immunohistochemistry with mismatch-repair (MMR) status, tumor-infiltrating lymphocytes, tumor cell PD-L1 expression, and clinicopathological characteristics in 507 CRC patients. Although 91.9% of CRCs showed negative or weak Tn antigen staining (Tn-negative/weak), we identified a small subset of CRCs (8.1%) that displayed particularly intense and diffuse distribution of Tn antigen immunoreactivity (Tn-strong) that closely related to deficient MMR (dMMR). Moreover, 40 dMMR CRCs were stratified into 24 Tn-negative/weak dMMR tumors (60.0%) exhibiting dense CD8+ lymphocyte infiltrate concomitant with a high rate of PD-L1 positivity, and 16 Tn-strong dMMR tumors (40.0%) that demonstrated CD8+ T cell exclusion and a lack of PD-L1 expression, which was comparable to those of proficient MMR. Our finding suggests that the immune cold subset of patients with Tn-strong dMMR CRC may be effectively treated with immune checkpoint blockade therapy or cellular immunotherapy targeting Tn antigen.

KRT17 as a prognostic biomarker for stage II colorectal cancer

Adjuvant chemotherapy is considered for patients with stage II colorectal cancer (CRC) characterized by poor prognostic clinicopathological features; however, current stratification algorithms remain inadequate for identifying high-risk patients. To develop prognostic assays, we conducted a step-wise screening and validation strategy using nine cohorts of stage II patients based on multiple platforms, including microarray, RNA-sequencing (RNA-seq) and immunohistochemistry (IHC) on formalin-fixed paraffin-embedded (FFPE) tissues. Four microarray datasets (total n = 458) were used as the discovery set to screen for single genes associated with postoperative recurrence. Prognostic values of candidate genes were evaluated in three independent microarray/RNA-seq validation cohorts (n = 89, n = 93 and n = 183, respectively), and then IHC for KRT17 was conducted in two independent FFPE series (n = 110 and n = 44, respectively). We found that high levels of KRT17 transcript expression were significantly associated with poor relapse-free survival (RFS) not only in the discovery set, but also in three validation cohorts, and its prognostic impact was independent of conventional factors by multivariate analyses. Positive staining of KRT17 protein was significantly associated with poor RFS in two independent FFPE cohorts. KRT17 protein expression had independent prognostic impact on RFS in a multivariate model adjusted for conventional variables, including high-risk clinicopathological features. In conclusion, using nine independent cohorts consisting of 997 stage II patients, we identified and validated the expression of KRT17 transcript and KRT17 protein as a robust prognostic biomarker that can discriminate postoperative stage II patients who are at high probability of disease recurrence, providing additional prognostic stratification beyond the currently available high-risk factors.

Where are we with pre-exposure prophylaxis use in Central and Eastern Europe? Data from the Euroguidelines in Central and Eastern Europe (ECEE) Network Group

OBJECTIVES

Pre-exposure prophylaxis (PrEP) for HIV infection is an important intervention for control of the HIV epidemic. The incidence of HIV infection is increasing in the countries of Central and Eastern Europe (CEE). Therefore, we investigated the change in PrEP use in CEE over time.

METHODS

The Euroguidelines in Central and Eastern Europe (ECEE) Network Group was initiated in February 2016 to compare standards of care for HIV and viral hepatitis infections in CEE. Data on access to PrEP were collected from 23 countries through online surveys in May-June 2017 (76 respondents) and in November 2018-May 2019 (28 respondents).

RESULTS

About 34.2% of respondents stated that tenofovir/emtricitabine (TDF/FTC) was licensed for use in their country in 2017, and 66.7% that it was licensed for use in 2018 (P = 0.02). PrEP was recommended in national guidelines in 39.5% of responses in 2017 and 40.7% in 2018 (P = 0.378). About 70.7% of respondents were aware of "informal" PrEP use in 2017, while 66.6% were aware of this in 2018 (P = 0.698). In 2018, there were 53 centres offering PreP (the highest numbers in Poland and Romania), whereas six countries had no centres offering PreP. The estimated number of HIV-negative people on PreP in the region was 4500 in 2018. Generic TDF/FTC costs (in Euros) ranged from €10 (Romania) to €256.92 (Slovakia), while brand TDF/FTC costs ranged from €60 (Albania) to €853 (Finland).

CONCLUSIONS

Although the process of licensing TDF/FTC use for PrEP has improved, this is not yet reflected in the guidelines, nor has there been a reduction in the "informal" use of PrEP. PrEP remains a rarely used preventive method in CEE countries.

A TGFβ-Dependent Stromal Subset Underlies Immune Checkpoint Inhibitor Efficacy in DNA Mismatch Repair-Deficient/Microsatellite Instability-High Colorectal Cancer

Patients with DNA mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) colorectal cancer represent a biomarker-defined population with distinct clinicopathologic features who are susceptible to immune checkpoint inhibitors (ICI). However, their survival outcomes vary considerably and nearly half of them exhibit primary resistance to current ICIs, suggesting substantial molecular heterogeneity even among tumors with dMMR/MSI-H. We conducted an extensive analysis of the tumor microenvironment (TME) using multiple transcriptomic, proteomic, and IHC cohorts of colorectal cancer, comprising 222 dMMR/MSI-H and 1440 MMR-proficient/microsatellite stable tumors. We developed a TGFβ-responsive stromal gene signature and then identified a unique poor prognostic subgroup of patients with dMMR/MSI-H colorectal cancers, characterized by the upregulation of transcriptional programs, including the TGFβ-rich active TME, angiogenesis, M2 macrophage polarization, and the extracellular matrix signature predictive of ICI resistance. The TGFβ-dependent stromal subset within dMMR/MSI-H tumors exhibiting poor survival outcomes was further recapitulated by proteomic datasets and IHC for VCAN protein expressed by cancer-associated fibroblasts. Meanwhile, this dMMR/MSI-H stromal subgroup was enriched neither with CD8⁺ T-cell infiltration nor common genomic alterations, such as mutation density and BRAF mutations, compared with dMMR/MSI-H tumors without TGFβ-dependent stromal activation. In conclusion, this study revealed a novel stromal subgroup of patients with dMMR/MSI-H colorectal cancer, demonstrating a TGFβ-rich tumor-promoting TME and unfavorable survival outcomes. IMPLICATIONS: Dual inhibition of immune checkpoints and TGFβ signaling may offer a promising strategy for these patients.

[A Case of Rectovaginal Fistula after Rectal Cancer Surgery Cured with Estriol Vaginal Tablet and Vaginal Lavage]

Although rectovaginal fistula is a rare complication of rectal cancer surgery, it is usually difficult to cure with conservative treatment, and patients generally need surgical intervention. A woman in her 70s underwent laparoscopic low anterior resection with right lateral lymph node dissection for rectal cancer. On postoperative day(POD)6, she had an anastomotic leakage and received conservative treatment. On POD 9, she underwent emergent laparotomy for urinary peritonitis as well as ileostomy and ureteral stenting. On POD 21, the rectovaginal fistula was confirmed with lower gastrointestinal tract fluoroscopic examination. The patient received conservative therapy for the rectovaginal fistula with estriol vaginal tablets and vaginal lavage for 2 weeks. Subsequently, the fistula was completely cured. After continuation of the estriol vaginal tablets for 4 weeks, the rectovaginal fistula has not recurred at the most recent follow-up.

[A Case of Simultaneous Recurrence of Colon Cancer at the Drain Placement and Anastomotic Sites Postoperatively]

A woman in her 70s presented to our hospital with abdominal pain and right lower abdominal mass. Colonoscopy revealed circumferential ascending colon cancer. She underwent right hemicolectomy, D3 lymphadenectomy, and ileocolonic functional end-to-end anastomosis. The tumorwas pathologically diagnosed as T4aN1M0, Stage Ⅲa. Nine months afterthe first surgery, tumor marker levels increased, and detailed examination yielded a diagnosis of isolated recurrence at the site of drain removal in the abdominal wall. The tumor was resected without exposure. Four months after the second surgery, the tumor recurred in the abdominal wall. Furthermore, colonoscopy revealed anastomotic recurrence. Both recurrent tumors at the anastomotic site and in the abdominal wall were resected. No more recurrence has been detected to date. In this case, a possible cause of recurrence is implantation of cancer cells. Sufficient consideration should be given to innovations in intraoperative maneuvers and surgical wound protection, among others.

[A Case Receiving Gastric Tube Resection for the Recurrence after a Proton Beam Irradiation in a Patient with Gastric Tube Cancer after Esophagectomy]

A 74-year-oldman underwent transthoracic esophagectomy andgastric tube reconstruction for esophageal cancer 15 years ago. Eleven years after the esophagectomy, he was diagnosedwith gastric tube cancer. He receivedproton beam irradiation therapy. Macroscopic clinical effect revealed complete response at that time. Four years later, due to his discomfort symptom, he was diagnosedwith recurrent gastric tube cancer. Total resection of the gastric tube was performedat our hospital. In pathology findings, poorly differentiated adenocarcinoma was found at the proton beam irradiated part with multiple lymph node metastases in the omentum. He died 8 months postoperatively because of carcinomatous pleurisy. Periodic screening of the gastric tube and early detection of gastric tube cancer at early stage are important.

[A Case of Long-Term Survival of Metastatic and Recurrent Duodenal Gastrointestinal Stromal Tumor Treated with Multimodality Managements]

We hereby report a case of long-term survival of metastatic and recurrent duodenal gastrointestinal stromal tumor(GIST) treated with multimodality managements. A 59-year-old man was diagnosed with duodenal GIST and underwent surgical resection of a primary lesion of the duodenum. Since the pathological findings on mitotic rate indicated its high risk of recurrence, the systemic treatment by imatinib mesylate was given shortly after the surgery. Six months later, metastatic lesions being considered to be imatinib-resistant were observed in the remnant liver. Since there were no other drugs available for GISTs in clinic at that time, surgery of central bisegmentectomy with partial resection of the liver was performed to eliminate all metastatic lesions. However, recurrences had been repeatedly diagnosed afterward. In response to them, four more surgery for recurrent liver or peritoneal tumors, two transcatheter arterial chemoembolizations(TACE)and one radiofrequency ablation(RFA)were performed on the basis of its resectability. Sunitinib malate had been given since it was approved for imatinib-resistant GISTs in clinic. Eventually, as long as 99 months had passed since we observed the first evidence of the resistance to imatinib mesylate when he died from the GIST.

[A Case of Long-Term Survival of the Pancreatic Tail Cancer with the Concomitant Small Liver Metastasis]

We hereby report a case of long-term survival of the pancreatic tail cancer with a synchronous small liver metastasis. A 62- year-old male with pancreatic tail cancer was incidentally diagnosed with single tiny metastasis in the left medial section of the liver duringthe distal pancreatectomy. The lesion was also resected together with primary lesion. Since then, systemic chemotherapies such as gemcitabine(GEM)plus S-1 combination therapy, GEM alone therapy and S-1 alone therapy had been given to escape from recurrence. However, the recurrences were found in the liver at 21 months after surgery. Left hepatectomy was performed for metastatic lesions. Afterwards, proton radiation therapy was twice performed for the metastatic lesions in the liver which were unable to be removed by surgery alone. Partial resection of transverse colon was also needed to be performed for the bowel obstruction caused by recurrence on the surgical margin of the liver. Systemic chemotherapies includingS -1 therapy, FOLFIRINOX therapy and GEM plus nab-paclitaxel therapy have been continued throughout his entire treatment history after recurrence. He has been keepingin good physical condition with these multidisciplinary therapies, even though 51 months have passed since the first evidence of liver metastasis was diagnosed.

[Risk Evaluation and Prognostic Prediction of Colorectal Cancer in Elderly Patients Over 80 Years of Age]

This study aimed to investigate risk factors and prognosis ofcolorectal cancer in patients over 80 years ofage. Surgical risk was evaluated by colorectal POSSUM(CR-POSSUM)and prognosis by Glasgow prognostic score(GPS). The analysis included 56 patients aged over 80 years with colorectal cancer during 2002-2012. Mean operation time, blood loss, and period ofhospitalization were 130 min, 111 mL, and 19.9 days, respectively. Postoperative complications occurred in 26 patients (46.4%; complications group). The 5-year overall survival rate for patients with complication scores above 2 was 51.1%, compared to 82.3% in a control group, and patients in the complication group also exhibited a poorer prognosis. CR-POS SUM scores were significantly higher in the complication group than in the control group in PS, OS, and PMR. Further analysis revealed that patients with GPS 0 or 1 had a significantly higher 5-year survival rate(84.9%)than those with GPS2(38.9%, p <0.05).

[A Case of Port Site Recurrence after Laparoscopic Distal Gastrectomy for Advanced Gastric Cancer]

It has been suggested that port site recurrence is a potential complication after laparoscopic distal gastrectomy for gastric cancer, especially considering the increased number of laparoscopic surgeries being performed. We encountered a case of an 84-year-old man who was diagnosed with 2 port site recurrences at the navel and right hypochondrium after laparoscopic distal gastrectomy(D2). Pathological diagnosis for the original tumor was tub2, pT4a, pN1(1/38), M0, pStage III A, and HER2(0). As first-line chemotherapy with S-1 plus CDDP for the port site recurrence failed, second-line chemotherapy with ramucirumab plus paclitaxel(RAM plus PTX)was administered. Although RAM plus PTX therapy induced shrinkage of the port site recurrence, liver metastasis was detected as a new lesion. RAM mono-therapy maintained good QOL for 18 months after surgery.

[Deceased Schizophrenic Patients--Focus on QT Prolongation]

We retrospectively evaluated factors affecting the lifespan of schizophrenic patients, who are known to have a shorter life expectancy than healthy people, focusing on the relationship with QT prolongation associated with antipsychotics. In a total of 406 patients who died at Asai Hospital the mean age at death was compared between schizophrenic patients and nonpsychiatric patients. In deceased schizophrenic patients, drug-related factors, hematology results, and electrocardiographic findings for 3 years before death were compared with those for the same period in age-matched surviving schizophrenic patients. In addition, QT values in schizophrenic patients and healthy controls were evaluated by age group. The mean age at death was significantly younger in schizophrenic patients (63.4 +/- 2.63 years) than in nonpsychiatric patients (84.0 +/- 0.57 years) (p<0.001). Bivariate analysis between deceased and surviving schizophrenic patients showed significant differences in QT values at 2 years, 1 year, and 0.5 years before death and in AST and ALT values at 0.5.years before death. The incidence of QT prolongation in deceased schizophrenic patients (52.0%) was about twice as high as that in surviving schizophrenic patients (24.5%). Multiple logistic regression analysis suggested that the proportion of deceased patients was higher when QT intervals were longer and ALT values were relatively higher, even if within the normal range. In both schizophrenic patients and medical checkup examinees, QT values were positively correlated with the age (R2 = 0.9061 and 0.9276, respectively), and QT intervals in schizophrenic patients were significantly longer in the 30- to 70-year age groups. In both schizophrenic patients and medical checkup examinees, QT values were positively correlated with the age, and QT intervals in schizophrenic patients were significantly longer than those in medical checkup examinees in the same age groups. Deceased schizophrenic patients showed significantly longer QT intervals from 2 years before death than age-matched surviving schizophrenic patients. QT prolongation may influence the lifespan of schizophrenic patients, which are shorter than those of nonpsychiatric patients. This highlights the importance of following electrocardiographic findings and hematology results of schizophrenic patients over time.

Three-dimensional STEM for observing nanostructures

A new scanning transmission electron microscope has been developed for three-dimensional (3D) observations of nanostructures. Using double spherical fulcra, accurate eucentric rotation was achieved. Cylindrical specimens for 3D-observation were prepared by a microsampling technique using a focused ion beam. Copper via-holes of a semiconductor memory device and ZnO particles were observed by the 3D-STEM from different directions, and 3D-data of the ZnO particles were successfully reconstructed in a topography mode.

Successful angioplasty of the left pulmonary artery using the vascular clip system

Pulmonary angioplasty was successfully performed in two patients using the vascular clip system (VCS). The portion of the pulmonary artery which was directly invaded by primary lung cancer was partially resected. The VCS was used to quickly and easily repair the vascular defect. No bleeding was noted from the clipped vascular walls. Both patients had uneventful recoveries.

Staple-line reinforcement with a new type of polyglycolic acid felt

Although various materials have been used for reinforcement in lung-volume-reduction surgery to buttress pulmonary staple-line, absorbable materials are not available for use in thoracoscopic surgery. Moreover, even nonabsorbable types of reinforcements have been used only for lung volume reduction surgery. However, elderly patients with spontaneous pneumothorax secondary to emphysematous lung are well treated with staple-line reinforcement. The authors developed a new type of polyglycolic acid felt to buttress staple-line. This felt is absorbable, easier to cut with a stapler knife than is the conventional polyglycolic acid felt, and inexpensive enough to use for various types of thoracic surgeries for emphysematous lungs in Japan, and it can be attached to staplers with a small amount of fibrin glue. These strips were used to reinforce pulmonary staple lines for resection of emphysematous lungs in 14 patients: pulmonary emphysema (n = 1), bilateral giant bullae (n = 1), ipsilateral giant bullae (n = 6), spontaneous pneumothorax with multiple bullae in an emphysematous lung (n = 5), and lung cancer in a patient with pulmonary emphysema (n = 1). There were no air leaks during surgery. Air leaks were noted in three patients after surgery. In two patients, the air leaks stopped within 2 weeks. In one patient, the air leak was found to originate from an untouched lobe during reoperation. No infection or allergic reaction developed in a patient during a mean follow-up of 12 months (range, 1 to 24 months).

[A case of pulmonary arteriovenous fistula associated with cerebellar abscess]

We report a rare case of pulmonary arteriovenous malformation (PAVM) with cerebellar abscess. The patient was 38-year-old woman who admitted to the local hospital for headache and fever. Subsequently, her condition became critical with consciousness disturbance, and hypoxemia. Brain computed tomography (CT) and chest CT revealed cerebellar abscess and PAVM. She was referred to our hospital for the surgery. Pulmonary angiography demonstrated multiple pulmonary arteriovenous fistulas in the right middle lobe and a single nodular pulmonary arteriovenous fistula in the right S8 (10 x 10 mm). After the drainage for the brain abscess, lobectomy of the right middle lobe and the excision of the nodal fistula in the right S8 were successfully performed in the two-staged operation. The patient has done well with no complication and her hypoxemia was improved.

Autopsy study of Alzheimer's disease brain pathology in schizophrenia

The brains of 125 schizophrenic patients (DSM-IV criteria) without other major diseases likely to affect brain morphology were examined at autopsy in our hospital for an evaluation of the number of neurofibrillary tangles (NFT) and senile plaques (SP) as indicators of the incidence of Alzheimer's disease (AD) brain pathology. The clinical degree of dementia and the presence or absence of delirium and Parkinsonism were determined in a review of the patients' charts. No significant difference in the degree of AD brain pathology between the 12 schizophrenics more than 75 years old and 12 age-matched normal controls was present. We conclude that AD pathology seems to be no more frequent among schizophrenic patients than in the normal population, and that the severe cognitive impairment observed in schizophrenics is based on neither neuronal degeneration nor neuronal loss like that occurring in AD. We believe that future morphological studies of cognitive impairments in schizophrenics will require a more detailed investigation at the receptor level.

[An elderly patient with progressive supranuclear palsy without neurological signs]

We report an elderly patient with progressive supranuclear palsy (PSP) who showed no neurological signs clinically. A 70-year-old man presented with irritation and poor hygiene, thereafter he showed excitement and violence. A cranial CT scan revealed bilateral moderate atrophy of the temporal lobes and slight enlargement of the lateral ventricle. The brain stem was slightly atrophic. Although he died at the age of 80 years, he had no neurological signs throughout the clinical course. Neuropathological study showed typical findings of PSP, neuronal loss with gliosis and neurofibrillary tangles in the basal ganglia, amygdala, midbrain, pons, dentate nucleus and inferior olivary nucleus. Staining by Gallyas-Braak methods revealed argyrophilic and tau-positive glial fibrillary tangles in the cerebral cortex. Neurofibrillary tangles showed greater frequency than usual for the physiological level in that age group in the hippocampus regions as well as in the amygdala. The possibility that the psychotic symptoms, mainly personality change, are connected with the degeneration of limbic system is indicated. Since there have not been any previous reports of PSP without neurological signs, this case represents an important in terms of clinico-pathological variation of PSP. We suggest that there is discrepancy between symptomatic and neuropathological aspects in elderly patients with PSP.

Corticobasal degeneration with primary progressive aphasia and accentuated cortical lesion in superior temporal gyrus: case report and review

A 57-year-old woman showed progressive sensory aphasia as an initial symptom, and then developed total aphasia within 6 years and, finally, severe dementia. Neuropathologically, the cerebral cortex was most severely affected in the superior and transverse temporal gyri, and subsequently in the inferior frontal gyrus, especially in the pars opercularis. The degeneration in the subcortical grey matter was most severe in the substantia nigra, and it was moderate to mild in the ventral part of thalamus, globus pallidus and striatum. Cytopathologically, in addition to achromatic ballooned neurons, massive taupositive types of cytosekeletal abnormalities were observed both in neurons and glia, mainly in the degenerating region. This cytoskeletal pathology coincided with that reported in corticobasal degeneration (CBD). On Bodian staining, only a few neurofibrillary tangles were found in the entorhinal pre-alpha layer and substantia nigra. Pick's bodies and senile plaques could not be found. This case is thought to represent a type of CBD, but with its cortical lesion focus located in the speech area instead of the frontoparietal region. A survey of 28 pathologically evaluated cases of CBD revealed two similar cases, both of which began with progressive aphasia and presented cortical degeneration in the superior temporal gyrus. An overview of CBD cases clarified the features in another group of cases, in which the cerebral accentuated focus was shifted forward from the central region, clinically resembling Pick's disease. The clinical manifestations in CBD seem to be the expression of these diverse cortical lesions. Primary progressive aphasia may include cases of CBD with involvement of the language center.

[An autopsy case of "diffuse neurofibrillary tangles with calcification", multiple infarctions and hyaline arteriosclerosis]

"Diffuse neurofibrillary tangles with calcification (DNTC)" is a slowly progressive form of presenile dementia characterized by localized temporal atrophy, pronounced calcareous deposits and numerous neurofibrillary tangles (NFTs) without senile plaques. We report a 70-year-old woman with DNTC, multiple infarctions and hyaline arteriosclerosis. This case was clinically characterized by persistent delusional ideas and personality changes. Intellectual deterioration was mild, and no focal manifestations were noted. Neuropathologically, numerous NFTs were seen distributed primarily in the hippocampal region, and massive calcareous deposits were observed in the cerebrum, basal ganglia and cerebellum. There were no senile plaques. Although the findings in this case were compatible with a diagnosis of DNTC, certain additional findings were also noted. The first was the presence of multiple infarctions in the basal ganglia and hyaline arteriosclerosis. Although these lesions may have been induced by hypertension, our review of previous reports of DNTC revealed a high incidence of arteriosclerosis. The second was the absence of lobar atrophy, which may have been due to the cerebral edema caused by the subdural hemorrhage or related to the relatively short duration of the illness. The dilatation of the temporal horn of the lateral ventricle and prominent NFTs in the hippocampal region indicate the initial occurrence of the disease in this region.

A comparative study of axillar hair removal in women: plucking versus the blend method

Fourteen healthy adult Japanese females were selected to participate in a comparative study of hair plucking (a temporary hair removal technique) and the blend method (a permanent hair removal technique). The effectiveness of permanent hair removal and the safety of the blend method were examined in this study. If hairs of the left axilla were removed by the blend method, then hairs of the right axilla were removed by plucking, and vice versa. Every hair was removed and the number of hairs was counted each time. Sessions were conducted every three weeks, and the experiment continued until no new hair growth was seen using the same experimental standard. Electrologists with more than 1000 hours of experience were selected to perform electrolysis. Examinations of the axilla, before and after each test, were conducted by the authors. The results showed that the number of hairs decreased in the axilla with each session using the blend method: permanent hair removal was achieved in an average of 26.8 weeks or 9.9 sessions. However, the number of hairs did not decrease in the axilla after plucking. Also, there were no reports of hair removal related side-effects in this study. It was thus demonstrated that the blend method is a safe and effective way of achieving permanent hair removal.

Radon update: facts concerning environmental radon: levels, mitigation strategies, dosimetry, effects and guidelines. SNM Committee on Radiobiological Effects of Ionizing Radiation

The risk from environmental radon levels is not higher now than in the past, when residential exposures were not considered to be a significant health hazard. The majority of the radon dose is not from radon itself, but from short-lived alpha-emitting radon daughters, most notably 218Po(T1/2 3 min) and 214Po (T1/2 0.164 msec) along with beta particles from 214Bi (T1/2 19.7 min). Radon gas can penetrate homes from many sources and in various fashions. Measuring radon in homes is simple and relatively inexpensive and may be accomplished in a variety of ways. Although it is not possible to radon-proof a house, it is possible to reduce the level. In high radon areas, if the average level is higher than 4-8 pCi/liter (NCRP recommended level is 8 pCi/liter; EPA recommended level is 4 pCi/liter), appropriate action is advised. The shape of the dose response curves for miners exposed to alpha-emitting particles in the workplace is consistent with current biologic knowledge. It is linear in the low dose range and saturates in the high dose range. No detectable increase in lung cancer frequency is seen in the lowest exposed miners (those with exposures < 120 WLM, the relevant dose interval for most homes). Evidence for a health effect from radon exposure is based on data from animal studies and epidemiologic studies of mines. Extensive radiobiologic data predict a linear dose-response curve in the low dose region due to poor biological repair mechanisms for the high density of ionizing events that alpha particles create. However, no compelling evidence for increased cancer risks has yet been demonstrated from "acceptable" levels (< 4-8 pCi/liter).

Expression of carbohydrate antigens in human pulmonary adenocarcinoma

BACKGROUND

The altered and anomalous expression of carbohydrate antigens (CA) occur in patients with lung carcinomas.

METHODS

To investigate the relationship between prognosis and immunohistochemical findings of CA in serum and pulmonary adenocarcinomas (PA), PA specimens surgically resected from 102 patients were studied with the use of A, B, H, Lewis(Le)a, Le(b), Le(x), Le(y), sialyl Le(a) (FH-7), sialyl Le(x-i) (SLX) (FH-6), sialosyl Tn (TKH-2), and CA 19-9. The Lewis blood group types were determined by the dot blotting method on patients' serum using monoclonal anti-Le(a), Le(b), Le(x), and Le(y). Formalin-fixed paraffin-embedded PA sections were stained using the avidin-biotin-peroxidase complex methods.

RESULTS

There was no correlation between the patients' postoperative survival and tissue expression of CA, although survival correlated with the clinical stages, histologic differentiation of PA, and serum SLX in Stage 4. The higher the positive rate of both Le(b) and Le(y), the better their differentiation in PA specimens. Regardless of blood group type, PA showed high positive reactions for FH-6 (88%) and Le(y) (87%). The serum concentration of CA 19-9 correlated with immunohistochemical reactions of tumors (Spearman correlation coefficient = 0.33, P = 0.02). The expression of Le(a) in Lewis (a-b+) phenotype patients and Type 2 CA, such as Le(y) and FH-6, is characteristic in PA.

CONCLUSIONS

The findings suggest that CA tissue expression may not reflect postoperative survival length of patients with PA, but biological aberrant fucosylation or sialylation as well as morphologic alteration may occur in neoplastic cells.

[A case of atypical senile dementia of Alzheimer type]

We describe the autopsy finding in a male patient with senile dementia of unusually prolonged total duration, who had exhibited atypical neuropathologic findings. During clinical course, memory disturbance had been more prominent than deterioration of other cognitive functions. Neuropathologic examination revealed neurofibrillary changes which were prominent in the hippocampal region and scattered in the amygdala and in the predilection sites of the hypothalamus and brain stem. This distributional pattern was that in Alzheimer-type dementia. The most characteristic finding was scanty senile plaques, which were scattered predominantly in the basal and medial portion of the frontal lobe. Although the clinical course and pathological findings of this case were in slight degree and deviated from those in usual senile dementia, it is thought that the entity in this case was dementia of the Alzheimer-type.

Coexistence of paired helical filaments and glial filaments in astrocytic processes within ghost tangles

Ultrastructural examination of ghost tangles in an autopsy case of long-term Alzheimer's disease revealed, in addition to degenerate neurites containing paired helical filaments (PHF), astrocytic processes which included PHF. This finding suggests either that astrocytes in ghost tangles possess the capacity to produce PHF or that PHF are incorporated into astrocytes by endocytosis.

[Fluorescence polarization immunoassay of isepamicin in blood spotted on filter paper]

A simple method has been developed for the determination of the aminoglycoside antibiotic isepamicin (ISP) in whole blood, using dried blood spots (DBSs) on filter-paper. ISP in the DBSs were recovered most effectively in 0.5 M Na2HPO4-NaH2PO4 buffer (pH 7) by incubation for 30 minutes at 35 degrees C in an ultrafiltration tube. The eluates from the DBS papers were centrifuged at 3,000 x g for 10 minutes. The clear, colorless filtrates were transferred to an Abbott TDx cartridge for measurement by the fluorescence polarization immunoassay. The lower limit for the quantitative determination of ISP in the DBS was 2.5 micrograms per ml of whole blood. The method permits a simple collection of blood at a microliter level and should prove particularly useful for therapeutic drug monitoring of ISP in blood at effective levels in pediatric and geriatric patients.

[Activities and isozymes of adenosine deaminase and lactate dehydrogenase in tuberculous pleural effusion with special reference to the presence of mycobacterium tuberculosis]

We have previously shown that tuberculous pleurisy possesses a high level of adenosine deaminase (ADA) which is predominantly composed of ADA2. In this paper, we report the cases of tuberculous pleural effusion which contained mainly ADA1. In these cases, mycobacterium tuberculosis was positive by smear examination and/or culture and granulocytes were found to be major components. Analysis of lactate dehydrogenase (LDH) revealed that its activity was high and LDH5 occupied about 50% of total activity. In the tubercle bacillus negative cases, lymphocytes were the main components and the levels of LDH containing mostly LDH3 were low. It was assumed that the difference in LDH activity and isozyme pattern is due to the differential presence of leukocytes in pleurisy i.e., granulocytes and lymphocytes in tubercle bacillus positive and negative pleurisy, respectively. In conclusion, tuberculous pleural effusions can be divided into two groups on the basis of ADA and LDH activities and isozymes which may reflect the presence of mycobacterium tuberculosis.

[Thoracoscopic laser coagulation shrinkage of blebs in the treatment of spontaneous pneumothorax]

As a thoracoscopic treatment for spontaneous pneumothorax, electrocautery has been mainly used. But contact type electrocautery has a risk of perforation of blebs. We adopted carbon monoxide laser (wave length 5.4 microns) and good coagulation shrinkage of blebs could be obtained by non-contact irradiation. CO laser was delivered by As-S glass fiber and power of fiber tip was 2-4 W. Compared with Nd-YAG laser (wavelength 1.06 microns), CO laser showed lower risk of perforation of blebs. Thoracoscopic CO laser coagulation shrinkage of blebs proved to be a important method of treatment for patient of spontaneous pneumothorax.

The v-abl, c-fms, or v-myc oncogene induces gamma radiation resistance of hematopoietic progenitor cell line 32d cl 3 at clinical low dose rate

A variety of viral and cellular oncogenes have been described with differing mechanisms of action but with the common property of inducing morphologic alteration of cells in culture. Subclonal lines of oncogene expressing cells have been shown to produce tumors in vivo. Expression of the N-ras oncogene in embryo fibroblast NIH/3T3 cells has been demonstrated to increase radioresistance in vitro, and these results have been confirmed and extended to human cell lines expressing the c-raf oncogene. In the present report, we have examined the effects of expression of the c-fms, v-abl, or v-myc oncogene in a clonal hematopoietic progenitor cell line 32D cl 3. The 32D cell line is nonmalignant in vivo and is dependent upon a source of Interleukin-3 (IL-3) for growth in vitro. The radiation survival of 32D cl 3 cells transfected and expressed in the c-fms oncogene showed significant increase in the radioresistance at both 5 cGy/min and 116 cGy/min. A clone of 32D cl 3 transfected and expressing the v-myc oncogene demonstrated increased radioresistance at both dose rates. Results of split dose experiments suggested significant repair of sublethal irradiation damage of 32D-v-abl cells. Results were compared with expression of the same v-abl oncogene in the NIH/3T3 embryo fibroblast cell line. The data demonstrate that gamma irradiation resistance is significantly increased by each oncogene expressed in 32D cl 3 cells. The data on cell line 32D cl 3 may correlate with the radioresistance of v-abl expressing human hematopoietic cell malignancies treated by irradiation therapy.

[Therapeutic guide line for hemoptysis]

We report the result of treatment for thirty-two patients whose chief complaint was hemoptysis and represent the therapeutic guide line for hemoptysis. In thirty-two cases, there were twenty men and twelve women and average of age was fifty-two years old. Twenty-nine of them were chronic lung diseases such as tuberculosis and bronchiectasis and only three cases have malignant tumors. Two of them recovered with conservative therapy and bronchial arteriography (BAG) have been performed in thirty patients in order to determine the bleeding foci, BAG was failed in two cases, but these two cases have been recovered with following up, BAG was succeeded in twenty-eight cases and twelve cases of them could not been determined the bleeding foci by angiography and could be controlled using hemostatic and antibiotic agents. Embolization of bronchial arteries with gelatin sponge have been performed in sixteen cases and made success in eleven cases. In ten of these cases, BAE was effective less than two times. Only one of silicosis with restrictive lung function was considered contraindication of surgery and recovered by three times of BAE. Four cases of five uneffective BAE (rebleeding after two times of BAE) have been treated by operation in good course. But one case complicated with WPW syndrome has died because of aspiration pneumonia without operation. In our institute, the rate of operation for hemoptysis was low as 13% of thirty-two cases. In order to consider the indication of surgery, bronchial arteriography was essential to determine bleeding foci and BAE was effective in over 80% of hemoptysis.(ABSTRACT TRUNCATED AT 250 WORDS)

[Surgical treatment of pathological stage III and IV in non-small cell lung cancer with peripheral tumor of 3 cm or less in diameter]

Among 287 patients underwent pulmonary resection between Mar 1978 and Dec 1989, 49 were proved pathologically to have their primary tumor of 3 cm or less in the greatest dimension. Twelve of these 49 classified to stage III A by the modiastinal lymph node metastasis or stage IV by the pulmonary metastasis. The histologic type of tumor was adenocarcinoma in 10 and squamous cell carcinoma in 2. Mode of surgical treatment consisted of pneumonectomy in 2, lobectomy in 8, segmentectomy or wedge resection in 2, and complete mediastinal lymph node dissection was performed in all but 2. Survival rate in 1, 3, 5 year was 100%, 38.1% and 38.1% in 9 with stage III A disease, and 100%, 100% and 50% in 3 with stage IV disease, respectively, and significant difference was noted in comparison with control group with larger tumor in each stage (p less than 0.05). From these results, we concluded that patients with small primary tumor could expect longer survival after surgical treatment, even if mediastinal lymph node metastasis or pulmonary metastasis was present.

Enlargement of the anterior horn of the lateral ventricle in schizophrenic patients: chronological and morphometrical studies

The anterior horn and lateral ventricular sizes of the brain CT were selected for measurement and comparison between 47 schizophrenic patients and 48 neurotic cases, which constituted the control subjects. The ventricular brain ratio (VBR) and the linear ratio (LR 1-6) in multiple age groups were calculated, analyzed and compared using the Student's t test, the two-way ANOVA and Bonferroni's methods. It was found that the VBR of the anterior horn and modified bicaudate cerebroventricular index of the teenage schizophrenics were significantly greater than those of the teenage controls (p less than 0.01) and the ventricular sizes were not associated with the different stages of age except for the cases of the teenage group. These results support the hypothesis of previous investigators that the ventricular enlargement is present early in the course of schizophrenia and provide additional evidence that in teenage schizophrenic patients there is a tendency of the enlargement of the anterior horn of the lateral ventricle which may be related with a morphological vulnerability in the prefrontal cortex.

Hematopoietic stem cell- and marrow stromal cell-specific requirements for gamma irradiation leukemogenesis in vitro

The hematopoietic and stromal cell-specific properties of the cells involved in gamma irradiation leukemogenesis in vitro were defined. Cocultivation of clonal factor-dependent (FD), interleukin 3 (IL-3)-dependent cell lines 32D cl 3 or B6SUtA, or dual IL-3-/granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent cell lines FDC-P1 or bg/bg d64 was carried out with clonal stromal cell lines D2XRII, GB1/6, +/+ 2.4, or Sld3. FD cell lines were added to control or 5000-cGy-irradiated plateau phase monolayer cultures of each stromal cell line, and parameters of stem cell engraftment and malignant transformation in vitro were quantitated. Cobblestone island formation by FD cells, cumulative production of nonadherent hematopoietic cells, and evolution of tumorigenic factor-independent (FI) subclonal lines were quantitated over 5-8 weeks. There was no detectable evolution of FI sublines with 32D cl 3, B6SUtA, or bg/bg d64 cells cocultivated with control or irradiated Sld3 stromal cells. IL-3-dependent cell lines 32D cl 3 or B6SUtA formed small 10- to 49-cell cobblestone "clusters" at low frequency on control or irradiated D2XRII, showed limited proliferation for less than 1 week, and showed no detectable evolution of FI cell lines. Subclones of 32D cl 3 derived by transfection and expression of recombinant oncogenes v-sis, or c-myc, or the epidermal growth factor receptor remained factor dependent and did not transform to factor independence after cocultivation with irradiated stromal cell lines. In contrast, cell line bg/bg d64, and each of seven subclonal lines of FDC-P1, including subclones selected for growth in GM-CSF, formed abundant cobblestone island colonies of greater than or equal to 50 cells on irradiated D2XRII stromal cells, produced non-adherent cells over 5-8 weeks, and showed evolution of tumorigenic FI subclonal lines. The data provide evidence for stable biological differences in both the hematopoietic and stromal cell components of the in vitro model of gamma irradiation leukemogenesis.