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BACKGROUND: Although percutaneous central venous port (CVP) placement can be quickly performed using minimally invasive surgery, short- and long-term complications can occur. Beginner pediatric surgeons must overcome learning curves influencing operative time and complication rates. However, few studies have been conducted on the learning curve of ultrasound-guided percutaneous CVP placement. This study analyzed the progress, results, complications, and learning curve of ultrasound-guided percutaneous CVP placement in children performed by a single beginner pediatric surgeon. METHODS: Data from 30 children who underwent ultrasound-guided percutaneous CVP placement were reviewed. The patient characteristics, procedure indications, access veins, operator positions, operative times, and complication rates were analyzed. RESULTS: Cumulative sum analysis revealed two stages in the learning curve: stage 1 (initial 15 cases) and stage 2 (subsequent cases). There was a correlation between the number of cases and operative time (Pearson correlation = -0.499, p = 0.005); the operative time was significantly longer in the first than in the second stage (p = 0.007). Although surgical complications occurred more frequently in the early (26.7%) than in the late stage, it was not significantly different between the two stages (p = 0.1). During the study period, the operative time was significantly reduced owing to the change in the operator's position from the patient's right side to the patient's head (p = 0.005). CONCLUSIONS: Ultrasound-guided percutaneous CVP placement was a safe surgery that allowed a beginner pediatric surgeon to overcome the learning curve after only 15 cases and involved a relatively small number of complications compared with other pediatric surgeries. Additionally, the suitable position of the operator affected the surgical outcomes.
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Cathétérisme veineux central , Courbe d'apprentissage , Durée opératoire , Échographie interventionnelle , Humains , Cathétérisme veineux central/méthodes , Mâle , Femelle , Enfant , Enfant d'âge préscolaire , Études rétrospectives , Nourrisson , Adolescent , Compétence cliniqueRÉSUMÉ
Objective: Choledochal cysts are increasingly being diagnosed antenatally. The appropriate time of surgical treatment has the greatest impact on the prognosis of choledochal cyst treatment. The purpose of this study was to compare the clinical outcomes of prenatally diagnosed choledochal cysts in infants according to the surgical treatment timing. Methods: We retrospectively reviewed the medical records of infants who underwent surgery for choledochal cysts with antenatal diagnoses. We investigated each patient's demographic information, type of choledochal cyst, serum liver enzyme levels, and surgical outcomes according to the surgical intervention timing. Results: Between May 2006 and December 2020, 93 infants underwent surgery to treat choledochal cysts; among them, 68 had antenatally suspected choledochal cysts. Of the 68 patients, 21 developed symptoms directly after birth. While 38 patients remained asymptomatic, 9 developed symptoms before operation. To compare surgical outcomes, asymptomatic patients were divided into early (13 cases) and late (25 cases) operation groups based on an age benchmark of 30 days. The early surgical group experienced longer times to resume a full diet (6.0 ± 1.6 vs. 4.5 ± 0.7, p < 0.001) and longer postoperative hospital stays (11 ± 3.9 vs. 7.5 ± 0.8, p < 0.001). Surgical complications occurred in two patients in the early operation group. Minimally invasive surgery was performed in 12 patients in the late operation group. In both groups, postoperative liver function recovered at 6 months, with no significant difference. Conclusion: The results of this study showed longer hospital stays, increased diet durations, and postoperative complications in early surgery patients. However, liver function recovery was not different between the early and late operation groups. Thus, asymptomatic patients should be closely monitored, and we recommend that definitive surgical intervention be postponed until 4 months of age or until weight reaches 7â kg.
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Bloodstream infection (BSI) after pediatric liver transplantation (PLT) is a common and severe complication that affects patient survival. Children with biliary atresia (BA) are at an increased risk for clinically significant infections. This study evaluated the impact of post-PLT BSI on clinical outcomes in children with BA. A total of 67 patients with BA aged <18 years who underwent PLT between April 2006 and September 2020 were analyzed and divided into two groups according to the occurrence of post-PLT BSI within 1 month (BSI vs. no BSI = 13 [19.4%] vs. 54 [80.6%]). The BSI group was significantly younger at the time of PLT and had a higher frequency of BSI at the time of PLT than the no BSI group. Early vascular complications within 3 months and reoperations were significantly more frequent in the BSI group. Univariate and multivariate analyses revealed that bacteremia within 1 month of PLT and graft-to-recipient weight ratio >4% were significantly associated with vascular complications. In conclusion, BSI after PLT is associated with increased vascular complications and reoperations. Proper control of bacterial infections and early liver transplantation before uncontrolled BSI may reduce vascular complications and unexpected reoperations in children with BA.
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This study aimed to report the surgical outcomes of laparoscopic glue hernioplasty (LGH) compared with conventional laparoscopic suture hernioplasty (LSH) in pediatric female inguinal hernia repair. We retrospectively analyzed 465 female pediatric patients who underwent laparoscopic inguinal hernia repair between January 2013 and December 2020. LGH and LSH were performed in 95 and 370 cases, respectively. Surgical outcomes (length of hospital stay, operative time, complications, and recurrences) were compared between the LGH and LSH groups. We found that the operation times for bilateral hernia repair were shorter in the LGH group (LGH: 35.5 ± 8.2 min, LSH: 45.2 ± 11.6 min; p < 0.001). No significant differences in complications or recurrences were observed between the two groups during the follow-up period. Our findings suggest that LGH is a feasible and easily applied surgical technique for the treatment of pediatric female inguinal hernia.
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BACKGROUND: This study aimed to report our experience with a robot-assisted resection of choledochal cysts (CCs) in pediatric patients, especially focusing on changes in outcomes and operative trends. METHODS: We retrospectively reviewed medical records of all 158 patients under 18 years of age who underwent robot-assisted resection of CC in a single tertiary center between July 2008 and January 2021. Patients were divided into the first period (P1, July 2008-March 2016; N = 79) and second period (P2, April 2016-January 2021; N = 79) with equal number of participants. The patients of P2 were compared with those of P1 to assess clinical outcomes with operative details. Operative characteristics and postoperative prognosis were compared for each group. RESULTS: The mean operative time was 383.6 min for the P2 group and 462.6 min for the P1 group (p < 0.001). The mean estimated blood loss was 28 mL in the P2 group and 63 mL in the P1 group (p = 0.025). The rate of emergency department visit after the operation was lower in the P2 group (3.8% vs. 13.9%, respectively, p = 0.047). The two groups showed no significant differences in the rate of late postoperative complications and reoperations. CONCLUSION: With the increase in the center's experience, robot-assisted resection of CC can be safely adopted and feasible, especially for pediatric patients. LEVELS OF EVIDENCE: Treatment Study, Level III.
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Kyste du cholédoque , Interventions chirurgicales robotisées , Robotique , Adolescent , Enfant , Kyste du cholédoque/chirurgie , Humains , Durée opératoire , Complications postopératoires/épidémiologie , Complications postopératoires/étiologie , Études rétrospectives , Résultat thérapeutiqueRÉSUMÉ
PURPOSE: There has been an increasing trend in the use of contralateral prophylactic mastectomy (CPM) among women diagnosed with unilateral breast cancer or mutations in BRCA1 or BRCA2 to reduce the occurrence of contralateral breast cancer. This study aimed to examine trends in the CPM rate according to clinicopathologic and socioeconomic status at a single institution in Korea. METHODS: This study included 128 patients with mutations in BRCA1 or BRCA2. Patients were divided into a CPM group (n = 8) and a non-CPM group (n = 120) between May 2013 and March 2016. The main outcome variables, including epidemiology, clinical features, socioeconomic status, and tumor characteristics, were analyzed. RESULTS: A total of 8 CPMs were performed among 128 patients. All CPM patients were married. The proportion of professional working women was higher in the CPM group (P = 0.049). Most patients who underwent CPM graduated college, compared to less than a third of the non-CPM group (P = 0.013). The CPM group had a higher rate of visits to the Hereditary Breast and Ovarian Cancer (HBOC) clinic (P = 0.021). The risk-reducing salpingo-oophorectomy (RRSO) rate was significantly higher in the CPM group (P < 0.01). CONCLUSION: CPM rates were significantly different according to socioeconomic status. The CPM rate tends to increase in highly educated and professional working women. The socioeconomic status of patients is an important factor in the decision to participate in the HBOC clinic and undergo CPM or RRSO.
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Andrographolide, a natural compound isolated from Andrographis paniculata, has been reported to possess antitumor activity. In the present study, the effect of andrographolide in human gastric cancer (GC) cells was investigated. Andrographolide induced cell death with apoptotic and non-apoptotic features. At a low concentration, andrographolide potentiated apoptosis and reduction of clonogenicity triggered by recombinant human tumor necrosis factor-related apoptosis-inducing ligand (rhTRAIL). Exposure of GC cells to andrographolide altered the expression level of several growth-inhibiting and apoptosis-regulating proteins, including death receptors. It was demonstrated that activity of the TRAIL-R2 (DR5) pathway was critical in the development of andrographolide-mediated rhTRAIL sensitization, since its inhibition significantly reduced the extent of apoptosis induced by the combination of rhTRAIL and andrographolide. In addition, andrographolide increased reactive oxygen species (ROS) generation in a dose-dependent manner. N-acetyl cysteine prevented andrographolide-mediated DR5 induction and the apoptotic effect induced by the combination of rhTRAIL and andrographolide. Collectively, the present study demonstrated that andrographolide enhances TRAIL-induced apoptosis through induction of DR5 expression. This effect appears to involve ROS generation in GCs.
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Although tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent, a number of cancer cells demonstrate TRAIL resistance. To date, various molecular targets leading to TRAIL resistance have been elucidated by many researchers, but the mechanisms involved are still not fully understood. In the present study, we obtained TRAIL-resistant cells from the human hepatocellular carcinoma cell line HepG2 by exposing cells to recombinant human TRAIL (rhTRAIL), and determined a mechanism for TRAIL resistance. The selected TRAIL-resistant cells (HepG2-TR) were insensitive to rhTRAIL and triggered autophagy in response to rhTRAIL. The inhibition of autophagy by 3-methyladenine or the knockdown of ATG5 partially restored rhTRAIL-induced apoptosis and cytotoxicity, indicating that protective autophagy occurred in the cells. Notably, rhTRAIL-induced autophagy was mediated through DR4 in HepG2-TR cells, but not in parental HepG2 cells. In addition, the c-Jun N-terminal kinase was involved in DR4-mediated autophagy in HepG2-TR cells. Our results suggest a novel mechanism of TRAIL resistance which is regulated through alterations in DR4 function, which may extend our understanding of the mechanisms of TRAIL resistance.
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Autophagie/effets des médicaments et des substances chimiques , Carcinome hépatocellulaire/anatomopathologie , Résistance aux médicaments antinéoplasiques , Tumeurs du foie/anatomopathologie , MAP Kinase Kinase 4/métabolisme , Récepteurs de TRAIL/métabolisme , Ligand TRAIL/métabolisme , Antinéoplasiques/pharmacologie , Apoptose/effets des médicaments et des substances chimiques , Carcinome hépatocellulaire/traitement médicamenteux , Carcinome hépatocellulaire/métabolisme , Survie cellulaire/effets des médicaments et des substances chimiques , Humains , Immunotransfert , Tumeurs du foie/traitement médicamenteux , Tumeurs du foie/métabolisme , Transduction du signal/effets des médicaments et des substances chimiques , Cellules cancéreuses en cultureRÉSUMÉ
Castleman's disease (CD) is a rare lymphoproliferative disorder of unknown etiology. Clinically, it occurs as a localized (unicentric) disease or as a systemic (multicentric) disease. Unicentric Castleman's disease (UCD) presents as a solitary mass and primarily affects the mediastinal, retroperitoneal, and cervical lymph nodes. In contrast to multicentric CD, which involves peripheral lymphadenopathy and numerous systemic symptoms, UCD is not typically associated with generalized symptoms. Three main distinct histologic variants are recognized: hyaline-vascular type, plasma cell type, and mixed type. Extranodal CD is rare. Specifically, UCD exclusively in the spleen is extremely rare, with only 2 cases described in the literature to date. Here, we describe an asymptomatic 75-year-old man with a 5.7 cm × 4.5 cm sized heterogenous enhanced mass located in the spleen. He underwent surgical resection for diagnosis and treatment. A pathologic examination indicated the hyaline-vascular type of CD. In this patient, the preoperative diagnosis was difficult to determine, and therefore, invasive procedures were required.
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Hyperplasie lymphoïde angiofolliculaire/diagnostic , Maladies de la rate/diagnostic , Sujet âgé , Biopsie , Hyperplasie lymphoïde angiofolliculaire/chirurgie , Humains , Mâle , Valeur prédictive des tests , Splénectomie , Maladies de la rate/chirurgie , Tomodensitométrie , Résultat thérapeutiqueRÉSUMÉ
Recent studies have demonstrated that expression of the vvpE gene begins during the early growth phase albeit at low levels. However, we found that the traditional protease assay method that is used to measure caseinolytic activity in culture supernatants is not suitable for the measurement of extracellular VvpE that is produced at low levels during the early growth phase. By using gelatin-zymography in place of the protease assay, we could specifically detect only VvpE of several proteases produced by Vibrio vulnificus. Moreover, we could sensitively measure VvpE produced at low levels during the early growth phase, which was consistent with transcription of the vvpE gene. The extracellular production of VvpE was reduced or delayed by mutation of the pilD gene which encodes for the type IV leader peptidase/N-methyltransferase associated with the type II general secretion system; the delayed production of VvpE was recovered by in trans complementation of the wild-type pilD gene. These results indicate that VvpE begins to be produced during the early growth phase via the PilD-mediated type II general secretion system, and that the use of gelatin-zymography is recommended as a simple method for the sensitive and specific detection of VvpE production.
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Protéines bactériennes/biosynthèse , Techniques bactériologiques/méthodes , Metalloproteases/biosynthèse , Vibrio vulnificus/enzymologie , Protéines bactériennes/génétique , Gélatine/métabolisme , Délétion de gène , Régulation de l'expression des gènes bactériens , Test de complémentation , Metalloproteases/génétique , Transport des protéines/génétique , ARN bactérien/analyse , ARN bactérien/génétique , ARN messager/analyse , ARN messager/génétique , Sensibilité et spécificité , Transcription génétique , Vibrio vulnificus/composition chimique , Vibrio vulnificus/croissance et développementRÉSUMÉ
We present a case of OEIS complex (omphalocele, exstrophy of bladder, imperforated anus, spinal defect) combined with colonic agenesis and glomerulocystic kidney disease (GCKD). The baby was born at 35.2 weeks of gestational age, weighing 2.51 kg. A prenatal ultrasound examination showed spina bifida, hydroureter, and a unilateral polycystic kidney. The postdelivery examination, which included a physical examination, simple X-ray, and pelvic MRI, showed a lower abdominal wall defect through which a small pouch with a segment of bowel protruded, imperforated anus, ambiguous external genitalia, spina bifida with meningomyelocele at the lumbosacral junction, and nonunion of pubic symphysis. The baby underwent surgery, including nephrectomy, colostomy, and repair of the abdominal wall defect. In addition to the abnormalities mentioned, a tailgut as a result of colonic agenesis and 2 appendices were identified in the course of surgery. The result of histopathological examination confirmed the polycystic kidney identified as GCKD. These radiological, surgical, and histopathologic findings are consistent with the OEIS complex. The postoperative course was uneventful during a period of 4 months of follow up. We herein report a case of the very rare OEIS complex in a newborn male baby and review the available literature.
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Malformations multiples/anatomopathologie , Imperforation anale/anatomopathologie , Exstrophie vésicale/anatomopathologie , Hernie ombilicale/anatomopathologie , Polykystoses rénales/complications , Dysraphie spinale/anatomopathologie , Malformations multiples/imagerie diagnostique , Adulte , Imperforation anale/imagerie diagnostique , Exstrophie vésicale/imagerie diagnostique , Côlon/malformations , Côlon/imagerie diagnostique , Femelle , Âge gestationnel , Hernie ombilicale/imagerie diagnostique , Humains , Nouveau-né , Mâle , Polykystoses rénales/imagerie diagnostique , Polykystoses rénales/anatomopathologie , Grossesse , Troisième trimestre de grossesse , Dysraphie spinale/imagerie diagnostique , Échographie prénataleRÉSUMÉ
A di(2-ethylhexyl)phthalate (DEHP) was accidentally extracted from plastics in the process of purification of chemosensitizers reversing P-glycoprotein (Pgp)-mediated multidrug resistance (MDR). The purpose of this study was to investigate the Pgp-reversal activities of phthalates, which are endocrine-disrupting chemicals, by utilizing the Pgp-overexpressing leukemic cell line AML-2/D100. The phthalates includes DEHP, diethyl phthalate (DEP) and dibutyl phthalate (DBP). Of the tested phthalates, DEHP showed the highest Pgp-reversal activity and DEP the most potent drug-accumulating activity. On the other hand, they did not show any chemosensitizing activity against multidrug resistance associated protein-mediated MDR. The complete inhibition of Pgp by verapamil increased the cytotoxicity of DEHP, but neither DEP nor DBP had this effect, suggesting that DEHP alone may be a possible substrate for the Pgp. DEHP showed higher hydrophobicity than the other phthalates when determined by reverse phase-HPLC. In addition, DEHP, but not the others increased the ATPase activity in a concentration-dependent manner. This is the first report that phthalates can reverse Pgp-mediated MDR by increasing drug accumulation, as well as serving as substrates for the Pgp. It is thought that the hydrophobic characteristics of phthalates could play an important role in Pgp-inhibitory activity. Therefore, pharmaco- and toxicokinetic interactions between phthalates leached from medical PVC devices and substrates for the Pgp should be kept in mind.
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BACKGROUND: Primary ovarian leiomyoma is a very rare tumor and usually it is small, unilateral-, and concomitantly seen with uterine leiomyomata in middle-aged to postmenopausal women. CASE: We describe a case of huge, bilateral ovarian leiomyoma that was not associated with uterine tumor in a 17-year-old woman. The authors of this study documented the smooth muscle origin of the tumor with immunohistochemical studies, the available literature was reviewed and the possible histogenesis was discussed. CONCLUSION: We herein report a case of a rare primary bilateral ovarian leiomyoma in a young woman.
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Léiomyome/anatomopathologie , Tumeurs de l'ovaire/anatomopathologie , Adolescent , Femelle , Humains , ImmunohistochimieRÉSUMÉ
Reactive oxygen species (ROS) cause macromolecular damage and may play an important role in tumor development. Superoxide dismutase (SOD) and metallothionein (MT) serve as initial and final defense mechanisms, respectively, against ROS. We hypothesized that the inducibility of Mn-SOD and MT mRNA by paraquat, an intracellular superoxide generator, might be altered in lymphocytes of gastric cancer patients. The inducibility of Mn-SOD mRNA by paraquat in lymphocytes of 19 normal subjects and the 14 gastric cancer patients was 162.4 +/- 16.7% and 87.9 +/- 9.5%, respectively (P = 0.001). The inducibility of MT mRNA by paraquat in the normal subjects and the gastric cancer patients was 126.7 +/- 15.8% and 115.4 +/- 12.9%, respectively. This suggests that the failure of Mn-SOD mRNA induction by oxidative stress in peripheral lymphocytes may be involved in the development of gastric cancer and may be of value in predicting the future occurrence of gastric cancer. In addition, the wide variation in Mn-SOD and MT mRNA levels among normal subjects may reflect different susceptibilities to diseases including cancer.
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Lymphocytes/métabolisme , Stress oxydatif , Paraquat/pharmacologie , Tumeurs de l'estomac/métabolisme , Superoxide dismutase/biosynthèse , Adulte , Sujet âgé , Induction enzymatique , Femelle , Colorants fluorescents/métabolisme , Humains , Mâle , Métallothionéine/génétique , Métallothionéine/métabolisme , Adulte d'âge moyen , ARN messager/métabolisme , Espèces réactives de l'oxygène/métabolisme , Superoxide dismutase/génétiqueRÉSUMÉ
PURPOSE: In breast cancer, Her-2/neu amplification/overexpression predicts a poor clinical outcome, and enhanced survival benefits have been reported with Her-2/neu targeted therapy. Currently, there are several methods for assessing the amplification/overexpression of Her-2/neu, each having advantages and disadvantages. The aim of this work was to establish a reproducible, sensitive and specific method of testing for Her-2/neu, which could be used in diagnostic pathology laboratories. MATERIALS AND METHODS: We compared the immunohistochemistry (IHC) detection of Her-2/neu overexpression, with differential polymerase chain reaction (PCR) to assess the gene amplification of the Her-2/ neu, in 163 cases of invasive ductal carcinoma of the breast using paraffin-embedded tissue. In addition, assessment of the appropriate cut off points was established. RESULTS: The overexpression of the Her-2/neu was detected in 39 (23.9%) cases, and its amplification in 37 (22.7%) cases. The methods were positive in 21.5% of cases and negative in 74.8%. There was a 96.3% concordance between the two methods. The sensitivity and specificity of IHC, compared with PCR, were 94.6 and 96.8%, respectively. CONCLUSION: We conclude that the automation of PCR-based Her-2/neu testing approaches is expected to play an increasing role in the future of Her-2/neu testing. Also, we have demonstrated that IHC is a sensitive and specific method for assessing Her-2/neu stati in breast cancer, compared to PCR. The current study indicates that moderate, or strong, complete membrane staining in> or =10% of tumor cells provides an appropriate cut off point compared with PCR.
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Mantle cell lymphoma, blastoid variant (B-MCL), is a very rare type of non-Hodgkin's lymphoma exhibiting an aggressive clinical course. We describe a case of B-MCL showing generalized lymphadenopathy and leukemic conversion in a 62-yr-old man. The case was diagnosed and subclassified as B-MCL on the basis of cyto-morphology and immunophenotype. Microscopic examination of the peripheral blood (PB) showed a spectrum of cells ranging from small mature lymphocytes to medium- and large-sized lymphocytes with blast-like chromatin and prominent nucleoli. The lymphoma cells were monoclonal B cells with moderately intense surface IgM. They were CD5 positive, cyclin D1 positive, CD10 negative, and CD23 negative. The flow cytometric immunophenotyping and DNA ploidy analysis of the PB and material obtained by aspiration cytology supported the diagnosis of B-MCL. These findings underline the utility of aspiration cytology in diagnosing B-MCL when cytomorphologic examination is combined with flow cytometric analysis of immuno-phenotype and demonstration of proliferation markers.
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Lymphome à cellules du manteau/diagnostic , Marqueurs biologiques , Ponction-biopsie à l'aiguille , Division cellulaire , Cytométrie en flux , Réarrangement des gènes , Humains , Immunophénotypage , Noeuds lymphatiques/anatomopathologie , Lymphome à cellules du manteau/génétique , Lymphome à cellules du manteau/immunologie , Lymphome à cellules du manteau/anatomopathologie , Mâle , Adulte d'âge moyenRÉSUMÉ
BACKGROUND AND AIMS: It has been proposed that the expression of Fas ligand (Fas L) in tumors may play an important role in immune escape. This study was undertaken to test a 'counterattack' theory as a mechanism of immune escape in gastric carcinoma. METHODS: Expression of Fas and Fas L was examined in the human gastric cancer cell lines using reverse transcription-polymerase chain reaction. Cytotoxicity was determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. Apoptosis of target Jurkat cells was examined after coculture with the effector gastric cancer cells in vitro. Immunohistochemical staining was performed for the detection of Fas and FasL in tumor-infiltrating lymphocytes (TIL) and gastric cancer cells in vivo. Apoptosis was detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) method in vitro and in vivo. RESULTS: Fas and FasL mRNA were found to be differentially expressed in gastric cancer cell lines. The coculture experiment showed that apoptosis of Jurkat was induced by a FasL-overexpressing effector gastric cell SNU-484. In a Fas-expressing gastric cell SNU-638, Fas expression was upregulated by the treatment of gamma-interferon in a time- and concentration-dependent manner. SNU-638 treated with gamma-interferon was more sensitive to anti-Fas antibody-mediated cytotoxicity than was the control cell line, suggesting an increase of functional Fas in gastric cancer cells. The expression of FasL in gastric cancer cells and of Fas in apoptotic TIL was also detected in vivo. CONCLUSION: The data indicate that the FasL expression of gastric cancer cells supports a 'counterattack theory' in gastric cancer cells and that the upregulation of Fas by IFN-gamma in SNU-638 may accelerate the apoptosis pathway through the Fas and FasL interaction between gastric cancer cells and immune cells. This result is supported by the expression of FasL in gastric cancer cells and apoptotic TIL in vivo. It is implicated that the different biological behaviors of gastric cancer cells could be at least in part explained by Fas and FasL interaction with immune cells.