The effect of intraportal administration of prostaglandin E1 on liver blood flow and liver function

BACKGROUND/AIMS

Prostaglandin E1 (PGE1) exerts a hepatic cytoprotective action directly and indirectly through enhancing hepatic blood flow. Although PGE1 is usually administered systemically, more than 60% of PGE1 is inactivated during only a single passage through the lung. By administering PGE1 intraportally the intrahepatic level of this drug can be increased effectively and liver dysfunction might be prevented. In this study, the effect of intraportal administration of PGE1 to patients who underwent hepatectomy was estimated.

METHODOLOGY

Twenty patients who underwent hepatectomy from January 1995 to December 1996 were divided into 2 groups, i.e., a PGE1 group (n=8) and a control group (n=12). Laboratory data and hepatic portal blood flow were examined before and after hepatectomy. In the PGE 1 group, PGE 1 was continuously infused at a dose of 120 microg/day for 5 days through a catheter inserted into the portal vein via the gastroepiploic vein.

RESULTS

There was no difference in the post-operative change in aspartate aminotransferase (AST) or alanine aminotransferase (ALT) between the 2 groups. Elevation of total bilirubin was more significantly suppressed in the PG group than in the control group. Total branched-chain amino acids and the tyrosine ratio reached their peak on the 5th post-operative day (POD) and were significantly higher in the PG group. Post-operative portal blood flow was significantly increased in the PG group.

CONCLUSIONS

Our results indicated that continuous intraportal administration of small doses of PGE1 is effective for the protection of hepatic function after hepatectomy.

Intravascular ultrasonography for assessment of portal vein invasion by pancreatic carcinoma

Intravascular ultrasonography (IVUS) was performed to diagnose portal vein invasion by pancreatic carcinoma. In 55 patients with pancreatic carcinoma, the intravascular ultrasonographic catheter was introduced during operation through a branch of the superior mesenteric vein into the intrahepatic portal vein. The catheter was gradually withdrawn, and the cross-sectional images of the area under investigation were recorded. Altogether 45 patients underwent resection, and 34 underwent combined resection of the portal vein. The IVUS findings were compared with the histologic findings of the resected specimen, preoperative computed tomography (CT), and arterial portogram. The wall of the portal vein was visualized as an echogenic band with a thickness of 0.5 to 1.0 mm. A subtle portal vein invasion can be detected by observing this portal vein wall. For the diagnosis of portal vein invasion, the sensitivity, specificity, and overall accuracy of IVUS were 99.6%, 92.3%, and 94. 5%, respectively. The equivalent values for portography were 79.3%, 61.5%, and 70.9%; and those for CT were 82.1%, 74.1%, and 78.1%. IVUS provides more valuable and accurate information on portal vein invasion by pancreatic carcinoma than either CT or portography.

Interleukin-18 enhances antigen-induced eosinophil recruitment into the mouse airways

Interleukin-18 (IL-18) has recently been identified as an IFN-gamma-inducing factor. Previous studies have shown that CD4(+) T cells, IL-5, and TNF-alpha mediate, but IFN-gamma and IL-12 (via IFN-gamma production) inhibit antigen-induced eosinophil recruitment into the airways of sensitized mice. Here, we showed that the administration of recombinant murine IL-18 enhanced antigen-induced eosinophil recruitment into the trachea and bronchoalveolar lavage fluids (BALF) of sensitized mice in a dose-dependent manner. The administration of IL-18 enhanced antigen-induced IFN-gamma and TNF-alpha production, but not IL-5 production, in the BALF and lungs of sensitized mice. Neutralizing antibody against TNF-alpha prevented antigen-induced eosinophil recruitment into the BALF of sensitized mice. Although IL-18 enhanced antigen-induced airway eosinophilia, IL-18 did not affect antigen-induced airway hyperresponsiveness in sensitized mice. These results indicate that IL-18, unlike IFN-gamma and IL-12, enhances antigen-induced eosinophil recruitment into the airways in part by increasing antigen-induced TNF-alpha production of sensitized animals. These findings suggest that IL-18 may contribute to the development and exacerbation of airway inflammation in asthma.

Effects of chronic liver diseases on mitochondrial DNA transcription and replication in human liver

To evaluate the effects of chronic liver diseases on mitochondrial DNA (mtDNA) transcription and replication, nuclear respiratory factor-1 (NRF-1) mRNA, mitochondrial transcription factor A (mtTFA) mRNA, a RNA component of ribonuclease (RNase) for mitochondrial RNA processing (MRP), mitochondrial cytochrome b mRNA, and mtDNA were measured in normal, chronically viral-hepatitic and cirrhotic human livers. The mRNA levels of the regulatory factors for mitochondrial gene (NRF-1 and mtTFA) and cytochrome b were significantly increased by chronic hepatitis (160, 280, and 175%, respectively) compared with those in normal livers, but were not different between cirrhotic and normal livers. On the other hand, concentrations of mtDNA and RNA component of RNase MRP were not different among normal, chronically hepatitic, and cirrhotic livers. These results suggest that either persistent hepatitis viral infection or repeated cell necrosis and regeneration in chronically hepatitic liver may be associated with increase in mtDNA transcription.

Dermoid cyst of the spleen: report of a case

A rare splenic dermoid cyst in an 11-year-old girl is reported herein. The patient was referred to us with the chief complaint of acute-onset abdominal pain. The lesion was demonstrated by ultrasonography, computed tomography, and magnetic resonance imaging to be a cystic lesion containing serous fluid. A splenectomy was performed. Both histopathological and immunohistochemical findings demonstrated the cyst to be a dermoid cyst of the spleen. To avoid the risk of infection following splenectomy, polyvalent pneumococcus vaccine was administered. The patient recovered uneventfully. We performed immunohistochemical studies with cytokeratin and electron microscopy to determine the origin of the cyst.

[A case of local recurrence of rectal cancer responding to local intraarterial infusion therapy]

A 42-year-old male developed pain in the right gluteal region due to local recurrence after curative resection of advanced lower rectal cancer. Radiotherapy (60 Gy) was performed, but satisfactory results were not obtained. Therefore, a reservoir was placed lowing cannulation of the internal iliac artery. The chemotherapy, in addition to intravenous administration of low dose CDDP (20 mg), included local intraarterial infusion therapy with 5-FU (1,500 mg/5 hour) once per week. After 10 courses of this chemotherapy (total dose: CDDP, 200 mg; 5-FU, 15,000 mg), the pain decreased, and the tumor size was reduced without side effects, improving the patient's QOL. At present, multidisciplinary treatments including such chemotherapy and radiotherapy is performed for local recurrence of rectal cancer, but adequate results are often not obtained. Local intraarterial infusion chemotherapy via the internal iliac artery accompanied by changes in blood flow can be safely performed on an outpatient basis, and appears to be effective for local recurrence of rectal cancer.

Lack of responsiveness to TGF-beta1 in a thyroid carcinoma cell line with functional type I and type II TGF-beta receptors and Smad proteins, suggests a novel mechanism for TGF-beta insensitivity in carcinoma cells

Transforming growth factor-beta (TGF-beta) is a multifunctional cytokine. In the present study we have investigated the expression of TGF-beta receptors (TbetaR's) and SMAD proteins in non-neoplastic and neoplastic thyroid follicle cells. We found expression of all TbetaR's (type I, II and III) and SMAD proteins analysed (Smad2, Smad3, Smad4, Smad6 and Smad7). Five out of six human anaplastic thyroid carcinoma cell lines were growth inhibited by addition of TGF-beta1, and therefore considered to be TGF-responsive. One cell line however, HTh 7, did not respond to TGF-beta1 with growth inhibition, induction of the extracellular matrix protein fibronectin or immediate early genes junB, Smad6 and Smad7 mRNA. Analysis of the TGF-beta intracellular signalling pathway in HTh 7 cells showed that receptors were capable of signalling, e.g. Smad2 phosphorylation and SMAD nuclear translocation. In summary, our data shows abundant expression of TGF-beta signalling components in thyroid follicle cells, and the escape from TGF-beta sensitivity in one anaplastic thyroid carcinoma despite an apparently functional TGF-beta/SMAD-signalling pathway, indicating a novel mechanism for TGF-beta insensitivity.

Transient gene transfer and expression of Smad7 prevents bleomycin-induced lung fibrosis in mice

TGF-beta plays an important role in lung fibrosis, which is a major cause of suffering and death seen in pulmonary disease. Smad7 has been recently identified as an antagonist of TGF-beta signaling. To investigate whether this novel molecule can be exploited for therapy of lung fibrosis, we determined the effect of exogenous Smad7, introduced by a recombinant human type 5 adenovirus vector, on bleomycin-induced lung fibrosis in mice. C57BL/6 mice with bleomycin-induced lungs received an intratracheal injection of a recombinant adenovirus carrying mice Smad7 cDNA. These mice demonstrated suppression of type I precollagen mRNA, reduced hydroxyproline content, and no morphological fibrotic responses in the lungs when compared with mice administered adenovirus carrying Smad6 cDNA. In addition, we found that expression of Smad7 transgene blocked Smad2 phosphorylation induced by bleomycin in mouse lungs. These data indicated that gene transfer of Smad7 (but not Smad6) prevented bleomycin-induced lung fibrosis, suggesting that Smad7 may have applicability in the treatment of pulmonary fibrosis.

Human livers with cirrhosis and hepatocellular carcinoma have less mitochondrial DNA deletion than normal human livers

We measured the populations of mutated mitochondrial DNAs with the 7,436 bp or the 4,977 bp deletion from apparently normal human liver and human livers with chronic hepatitis, cirrhosis, and hepatocellular carcinoma. The amount of the mutated mitochondrial DNA was at the same level between normal and chronically hepatitic livers but was significantly lower in human livers with cirrhosis and hepatocellular carcinoma, especially the latter, suggesting that the mutated mitochondrial DNAs may be decreased with the progress of liver disease from chronic hepatitis to cirrhosis and hepatocellular carcinoma. This phenomenon is opposite to that occuring in the ageing process.

Differential inhibition of Smad6 and Smad7 on bone morphogenetic protein- and activin-mediated growth arrest and apoptosis in B cells

Smad6 and Smad7 prevent ligand-induced activation of signal-transducing Smad proteins in the transforming growth factor-beta family. Here we demonstrate that both Smad6 and Smad7 are human bone morphogenetic protein-2 (hBMP-2)-inducible antagonists of hBMP-2-induced growth arrest and apoptosis in mouse B cell hybridoma HS-72 cells. Moreover, we confirmed that the ectopic expressions of Smad6 and Smad7 inhibited the hBMP-2-induced Smad1/Smad5 phosphorylation. We previously reported that Smad7 is an activin A-inducible antagonist of activin A-induced growth arrest and apoptosis in HS-72 cells. Interestingly, although mRNA expression of Smad6 was induced by activin A in HS-72 cells, Smad6 showed no antagonistic effect on activin A-induced growth arrest and apoptosis. Moreover, we found that the ectopic expression of Smad7, but not Smad6, inhibited the activin A-induced Smad2 phosphorylation in HS-72 cells. Thus, Smad6 and Smad7 exhibit differential inhibitory effects in bone morphogenetic protein-2- and activin A-mediated signaling in B lineage cells.

Involvement of JAK2, but not PI 3-kinase/Akt and MAP kinase pathways, in anti-apoptotic signals of GM-CSF in human eosinophils

Granulocyte-macrophage colony-stimulating factor (GM-CSF) transmits anti-apoptotic signals in eosinophils and is involved in tissue eosinophilia at the site of allergic inflammation. We determined whether phosphatidylinositol 3-kinase (PI 3-kinase) and mitogen-activated protein kinase (MAP kinase) are involved in anti-apoptotic signals of GM-CSF in eosinophils. GM-CSF phosphorylated Akt, a downstream component of PI 3-kinase, and MAP kinases (ERK1 and ERK2) at 10 min after stimulation in eosinophils. GM-CSF prevented eosinophil apoptosis and sustained its survival during the 5-day culture. However, neither two PI-3 kinase inhibitors, wortmannin and LY294002, nor MEK inhibitor PD98059 inhibited GM-CSF-induced survival of eosinophils, although wortmannin and PD98059 inhibited GM-CSF-induced Akt phosphorylation and MAP kinase activation in eosinophils, respectively. In contrast, JAK2 inhibitor AG-490 inhibited both GM-CSF-induced JAK2 phosphorylation and cell survival in eosinophils. These results indicate that activation of JAK2, but not activation of PI 3-kinase/Akt and MAP kinase pathways, is critical for anti-apoptotic signals of GM-CSF in human eosinophils. Our findings suggest that manipulation of JAK2 activation would be useful for the treatment of allergic disorders.

The role of extended radical procedures in advanced gallbladder cancer

BACKGROUND/AIMS

Owing to recent advances in diagnostic and surgical techniques, aggressive operations for advanced gallbladder carcinoma are becoming more safe. However, the role of a radical operation in terms of long-term survival remains controversial. In this study, we reviewed our experience with gallbladder carcinoma and the literature to clarify the present status of this strategy.

METHODOLOGY

So far in our department, we have treated 88 patients with gallbladder carcinoma and resection was performed in 46 of them. Stages, operative procedures, results of pathologic examinations and the outcome of the resected cases were reviewed.

RESULTS

Only 6 of the 46 patients belonged to the early stage (stage I and II in Nevin staging system, or stage I in TNM staging system) and had a good prognosis. Cholecystectomy with regional lymph node resection was performed in 13 patients. In other patients, more radical procedures including adjacent organ resection were performed according to the spread of the cancer. Major hepatectomy and pancreatoduodenectomy were additionally performed on 8 and 6 patients, respectively. Portal vein resection and reconstruction were performed in 3 patients. The survival rate in advanced cases was poor, but we had 5 long-term (more than 4 years) survivors among 40 patients in the advanced stages. Moreover, one patient undergoing a combination of extended right lobectomy of the liver, pancreato-duodenectomy with portal vein resection and extended node resection of the paraaortic nodes, survived for 3 years and 3 months until she died of another disease.

CONCLUSIONS

The prognosis is still not good in patients with advanced gallbladder carcinoma even if radical resection is performed. However, a number of our patients who underwent radical surgery survived a long time.

Blood loss and ICG clearance as best prognostic markers of post-hepatectomy liver failure

BACKGROUND/AIMS

Hepatic failure after hepatic resection is a lethal complication. Various factors affecting the occurrence of hepatic failure were examined.

METHODOLOGY

The subjects were 315 patients who underwent hepatic resection for hepatocellular carcinoma during the 11-year period between 1985 and 1995. Univariate analyses of 14 variables were performed among living and dead patients after hepatic resection. With the significant prognostic variables obtained in the multivariate analysis, the predicted probability of death (PPD) was calculated for each patient.

RESULTS

There were 291 survivors and 24 patients with post-operative liver failure. Among the factors showing statistical or near significance in the univariate analysis, KICG and blood loss were disclosed to be factors independently correlating with survival. PPD was calculated for each patient according to the following equation: PPD = 1/Exp(1.6766 - 0.0004394 x blood loss + 16.69 x KICG) + 1. Assessing the goodness-of-fit model by Hosmer-Lemeshow test indicated the model seemed to fit quite well.

CONCLUSIONS

Minimizing the blood loss during hepatic resection is important to avoid post-operative liver failure. Careful hemostatic procedure is necessary for patients with unexpected massive blood loss during hepatic resection so as to prevent post-operative bleeding.

Lack of constitutive activation of MAP kinase pathway in human acute myeloid leukemia cells with N-Ras mutation

Mitogen-activated protein (MAP) kinases act as transducers of extracellular signaling via tyrosine kinase-growth factor receptors and G-protein-linked receptors to transcription factors. Constitutive activation of MAP kinase has been observed in a variety of solid tumors including renal cancer and breast cancer. Recently, we have reported that constitutively activated MAP kinase was observed in 50% of human primary acute myeloid leukemia (AML) cells. Ras is one of the components of G-proteins and transduces the signal from cytokine receptors to raf-1 theoretically resulting in the activation of MAP kinase pathway. In the present study, we have examined the correlation of Ras mutations and the activation of MAP kinase pathway in patients with AML. Twenty out of 22 AML cases with activating N-Ras mutations showed no phosphorylated forms of ERK2. ERK2 phosphorylation was tightly correlated with ERK1 phosphorylation and MAP kinase activity detected by in vitro kinase assay. Three samples with N-Ras mutations were stimulated with IL-3, GM-CSF and G-CSF separately but ERK2 activation was induced in none of these samples stimulated with these cytokines. In contrast, ERK2 was constitutively activated in all of four pancreatic carcinoma cases with K-Ras mutation at codon 12. These results suggest that function of the Ras mutations may be different between solid tumors, such as pancreatic carcinoma and colorectal carcinoma, and AML. Mutated Ras does not always stimulate MAP kinase pathway constitutively and may rather inhibit classical MAP kinase cascade in AML blasts from leukemia patients.

Rapidly enlarging esophageal duplication cyst

We report a rare esophageal duplication cyst, in a 12-year-old girl. The cyst had enlarged rapidly within 2 years. In December 1997, on admission, computed tomography and magnetic resonance imaging demonstrated a cystic mass in the pleural cavity. We resected the cyst and the adjacent lung. Histopathological examination revealed an esophageal duplication cyst. Her presenting symptoms of fever and cough may have been related to infection of the cyst.

Gene transfer with cationic lipid into human hepatocellular carcinoma in nude mice

BACKGROUND/AIMS

Using a cationic lipid, gene transfection into the tumor of a human hepatocellular carcinoma model in nude mice was attempted in order to explore the possibility of its use in gene therapy.

METHODOLOGY

A DNA-lipid complex was made by combining the cationic lipid distearyldimethyl ammonium bromide (DDAB) with pCMV sPORT expressing the reporter gene LacZ. The expression of this complex was first investigated in vitro against the human hepatocellular carcinoma cell line Li7HM. It was then injected directly into a hepatocellular carcinoma model tumor created by implanting Li7HM into the liver of BALB/c nu/nu mice, and the expression of LacZ was histologically evaluated.

RESULTS

LacZ gene was expressed in Li7HM in vitro with the optimized DNA-lipid complex. Cell toxicity was not a problem. Expression of LacZ was also seen in the mouse hepatocellular model tumor into which the complex had been injected, indicating successful gene transfection with this method.

CONCLUSIONS

Direct injection of a DNA-lipid complex into a mouse hepatocellular carcinoma model tumor is a safe and simple method of gene transfection, proving this to be a viable method of transfer for use in gene therapy.

Mucosa-associated lymphoid tissue (MALT) lymphoma of the thyroid: report of a case

The patient was 59-year-old Japanese woman who presented with a neck swelling. Ultrasonography and computed tomography demonstrated a round tumor in the thyroid right lobe measuring 2.5 x 1.5 cm in size. A right hemithyroidectomy with lymph node dissection was performed. Histopathological findings demonstrated low-grade B cell lymphoma of the mucosa-associated lymphoid tissue (MALT) associated papillary microcarcinoma. A previous report showed an excellent prognosis of MALT lymphoma of the thyroid without capsular invasion or lymph node involvement. We also describe the concept of MALT lymphoma as a primary lesion in which lymphoid tissue is not present in the normal state.

Ubiquitous localization of leukotriene A4 hydrolase in the rat nephron

BACKGROUND

Leukotriene (LT) B4 is a well-known inflammatory mediator and is implied to play some roles in glomerulonephritis. Although LTA4 hydrolase, a final-step key enzyme to produce LTB4, is located in glomerular mesangial cells, as well as in leukocytes, platelets, and endothelial cells, its precise distribution in the kidney other than in mesangial cells remains unknown. Therefore, we have investigated the localization of mRNA, protein, and enzyme activity of LTA4 hydrolase in the rat kidney.

METHODS

Microdissection reverse transcriptase-polymerase chain reaction was used for the determination of LTA4 hydrolase mRNA. The enzyme protein was detected by Western blot, and immunohistochemistry was performed. Finally, LTA4 hydrolase activity and LTB4 were assayed in kidney tissues.

RESULTS

LTA4 hydrolase mRNA was detectable in all microdissected nephron segments of the cortex and outer medulla. The corresponding size of approximately 70 kDa protein was shown in descending order in the inner medullary > outer medullary >/= cortical homogenates. The immunohistochemical study demonstrated the ubiquitous presence of the enzyme in all nephron segments of cortex, outer medulla, and inner collecting tubules. LTA4 hydrolase activity was detected in the inner medullary >/= outer medullary >/= cortical tissue homogenates. LTB4 was demonstrated in the inner medullary > outer medullary >/= cortical tissues during the basal condition, and was time-dependently increased by stimulation with arachidonic acid and ionomycin in the cytosolic fraction from outer medulla and in the glomerular suspension.

CONCLUSIONS

These results strongly suggest that renal tubular cells as well as glomerular cells have an LTB4-forming potency, which may participate in physiological and pathophysiological roles in the kidney.

Clinical significance of alpha-fetoprotein mRNA during perioperative period in HCC

BACKGROUND/AIMS

The presence of alpha-fetoprotein (AFP)mRNA in the peripheral blood of patients with HCC suggested that carcinoma cells still existed. We investigated the influence of an alternation of human AFPmRNA perioperatively detected in peripheral blood in matters of recurrence, prognosis and operative performance.

METHODOLOGY

Thirty-three patients with HCC were enrolled for this study. AFPmRNA in peripheral blood before the operation, and on 1, 3, 7, 14, 21 and 28 post-operative days was examined by means of the reverse-transcriptase polymerase chain reaction (RT-PCR).

RESULTS

In 18 of 33 patients (54.5%) with HCC, AFPmRNA was detected in peripheral blood pre-operatively. Ten of 22 (45.4%) who were detected with AFPmRNA in peripheral blood during the perioperative period were diagnosed with intrahepatic recurrence or distant metastasis within 12 months post-operatively. In contrast, 10 (90.8%) of 11 patients who were not detected with AFPmRNA in peripheral blood anytime during hospitalization were diagnosed as free of intrahepatic recurrence or distant metastases within 9 months after the operation.

CONCLUSIONS

These results suggested that an alternation of AFPmRNA from HCC patients' peripheral blood during the perioperative period by means of this technique may be a practical tool in the detection of early recurrence or distant metastases after surgery.

A case of solitary metastatic pancreatic cancer from rectal carcinoma: a case report

A 79 year-old male who had undergone resection of the rectum for rectal cancer was shown to have metastasis to the pancreas 11 years after surgery. The metastatic lesion was located at the tail and body of the pancreas, and was resected with distal pancreatectomy. The same patient also had metastasis to the lung 8 years after initial rectal surgery. Therefore, the course of metastasis to the pancreas was suggested to be from the metastatic lung tumor to the pancreas by hematogenous spread. The patient was considered disease-free 8 months after the pancreatectomy. Recent advances in the technology of diagnostic imaging have facilitated the selection of surgical therapy for metastasis to the pancreas in rectal cancer patients after follow-up by imaging diagnosis.

Intracellular signaling of osteogenic protein-1 through Smad5 activation

Smad proteins play pivotal roles in the intracellular signaling of the multifunctional transforming growth factor-beta (TGF-beta) family members downstream of serine/threonine kinase type I and type II receptors. Smad2 and Smad3 are specific mediators of TGF-beta and activin, while Smadl and Smad5 are involved in bone morphogenetic protein-2 (BMP-2) and BMP-4 signaling. Here we report that osteogenic protein-1 (OP-1), also termed BMP-7, binds predominantly to BMPR-IB in the rat osteoprogenitor-like cell line, ROB-C26. Smad1, Smad5, and Smad8, but not Smad2 and Smad3, were found to stably interact with the kinase-deficient BMPR-IB after it was phosphorylated by the BMPR-II kinase. In ROB-C26 cells, which express Smad2, Smad3, Smad4, and Smad5, OP-1 was found to stimulate the phosphorylation of Smad5. Whereas transfection of wild-type Smad5 enhanced the OP-1-induced response, transfection of wild-type Smad2 had no effect on OP-1 signaling. A Smad5-2SA mutant, in which the two most carboxy-terminal serine residues were mutated to alanine residues, was found to act as a dominant negative inhibitor of OP-1-induced responses upon its transfection into various cell types, including ROB-C26 cells, in contrast to ectopic expression of a Smad2-2SA mutant which was without effect. Smad5, therefore, is a key component in the intracellular signaling of OP-1.

Benign fibrous mesothelioma successfully treated by thoracoscope-assisted surgery: report of a case

We report herein the case of an 84-year-old man in whom a benign fibrous mesothelioma (BFM) was successfully treated by thoracoscope-assisted surgery. In September 1996, the patient underwent a sigmoidectomy for colon cancer, soon after which a followup examination disclosed a coin lesion on his chest X-ray film. The patient was readmitted to our hospital in November 1996 for further investigation of this tumor. A chest computed tomography scan revealed a 3.5 x 3.0 cm homogeneous tumor arising from the pleura. A needle biopsy was performed under ultrasonographic guidance, and the specimen was histopathologically diagnosed as a BFM. In view of his poor respiratory function, the tumor was excised by thoracoscope-assisted surgery. This case report serves to demonstrate the benefits of thoracoscope-assisted surgery for such patients.

Physical and functional interaction of murine and Xenopus Smad7 with bone morphogenetic protein receptors and transforming growth factor-beta receptors

Members of the transforming growth factor-beta (TGF-beta) family transmit signals from membrane to nucleus via intracellular proteins known as Smads. A subclass of Smad proteins has recently been identified that antagonize, rather than transduce, TGF-beta family signals. Smad7, for example, binds to and inhibits signaling downstream of TGF-beta receptors. Here we report that the C-terminal MAD homology domain of murine Smad7 (mSmad7) is sufficient for both of these activities. In addition, we show that mSmad7 interacts with activated bone morphogenetic protein (BMP) type I receptors (BMPR-Is), inhibits BMPR-I-mediated Smad phosphorylation, and phenocopies the effect of known BMP antagonists when overexpressed in ventral cells of Xenopus embryos. Xenopus Smad7 (XSmad7, previously termed Smad8) and mSmad7 are nearly identical within their bioactive C-domain, but have quite distinct N-domains. We found that XSmad7, similar to mSmad7, interacted with BMP and TGF-beta type I receptors and inhibited receptor-mediated phosphorylation of downstream signal-transducing Smads. However, XSmad7 is a less efficient inhibitor of TbetaR-I-mediated responses in mammalian cells than is mSmad7. Furthermore, overexpression of XSmad7 in Xenopus embryos produces patterning defects that are not observed following overexpression of mSmad7, suggesting that mSmad7 and XSmad7 may preferentially target distinct signaling pathways. Our results are consistent with the possibility that the C-domain of antagonistic Smads is an effector domain whereas the N-domain may confer specificity for distinct signaling pathways.