Mucosal barrier and immune mediators

The intestinal mucosa functions is an immunologic organ that plays a major role in the development of oral tolerance and host-defense mechanisms. Antigens must cross the intestinal epithelium in a controlled manner to interact with dendritic antigen-presenting cells, because bacteria or their products are a primary risk factor for the development of intestinal inflammation. Therefore, the regulation of the intestinal epithelial cell barrier is central to the development of intestinal immunity and inflammation, but the involved mechanisms are largely unknown. Intestinal barrier function relies on the formation of tight junctions at the apical contact areas of intestinal epithelial cells. Tight junctions have a highly dynamic structure whose permeability, assembly, or disassembly can be regulated by a variety of cellular and metabolic mediators, including cytokines, which have major functions in the immune system. Immune modulators control tight junction dependent intestinal barrier function during development, wound healing, and pathologic processes such as cancer, infection, and chronic inflammation.

Interleukin-2 receptor beta subunit-dependent and -independent regulation of intestinal epithelial tight junctions

Interleukin (IL)-15 is able to regulate tight junction formation in intestinal epithelial cells. However, the mechanisms that regulate the intestinal barrier function in response to IL-15 and the involved subunits of the IL-15 ligand-receptor system are unknown. We determined the IL-2Rbeta subunit and IL-15-dependent regulation of tight junction-associated proteins in the human intestinal epithelial cell line T-84. The IL-2Rbeta subunit was expressed and induced signal transduction in caveolin enriched rafts in intestinal epithelial cells. IL-15-mediated tightening of intestinal epithelial monolayers correlated with the enhanced recruitment of tight junction proteins into Triton X-100-insoluble protein fractions. IL-15-mediated up-regulation of ZO-1 and ZO-2 expression was independent of the IL-2Rbeta subunit, whereas the phosphorylation of occludin and enhanced membrane association of claudin-1 and claudin-2 by IL-15 required the presence of the IL-2Rbeta subunit. Recruitment of claudins and hyperphosphorylated occludin into tight junctions resulted in a more marked induction of tight junction formation in intestinal epithelial cells than the up-regulation of ZO-1 and ZO-2 by itself. The regulation of the intestinal epithelial barrier function by IL-15 involves IL-2Rbeta-dependent and -independent signaling pathways leading to the recruitment of claudins, hyperphosphorylated occludin, ZO-1, and ZO-2 into the tight junctional protein complex.

A novel sox gene, 226D7, acts downstream of Nodal signaling to specify endoderm precursors in zebrafish

Vertebrate endoderm development has recently become the focus of intense investigation. We have identified a novel sox gene, 226D7, which is important in zebrafish endoderm development. 226D7 was isolated by an in situ hybridization screening for genes expressed in the yolk syncytial layer (YSL) at the blastula stage. 226D7 is expressed mainly in the YSL at this stage and, during gastrulation, its expression is also detected in the forerunner cells and endodermal precursor cells. The expression of 226D7 is positively regulated by Nodal signaling. The knockdown of 226D7 using morpholino antisense oligonucleotides results in a lack of sox17-expressing endodermal precursor cells during gastrulation, and, consequently, lacks endodermal derivatives such as gut tissue. The effect is strictly restricted to the endodermal lineage, while the mesoderm is normally formed, a phenotype that is nearly identical to that of the casanova mutant (Dev. Biol. 215 (1999) 343). We further demonstrate that overexpression of 226D7 increases the number of sox17-expressing endodermal progenitor cells without upregulating the expression of the Nodal genes, cyclops and squint. Region-specific knockdown and overexpression of 226D7 by injection into the YSL suggest that 226D7 in the YSL is not involved in endoderm formation and 226D7 in the endoderm progenitor cells is important for endoderm development. Taken together, our data demonstrate that 226D7 is a downstream target of Nodal signal and a critical transcriptional regulator of early endoderm formation.

Clinical application of vacuum-assisted cardiopulmonary bypass with a pressure relief valve

OBJECTIVES

Hemodilution induced by cardiopulmonary bypass (CPB) often prevents open heart operations without blood transfusion because of a large CPB-priming volume. A vacuum-assisted venous drainage system appears to overcome this problem and our previous experimental study demonstrated the beneficial effect of a vacuum-assisted CPB with a pressure relief valve. In this study, we clinically applied this novel system, and evaluated its efficacy by comparing it with the results of a conventional siphon-dependent drainage system.

METHODS

Sixty patients undergoing open heart operation were divided into Group V (vacuum-assisted system, n=30) and Group S (siphon-dependent system, n=30). The vacuum-assisted system contains a powerful vacuum generator and a pressure relief valve to keep the negative pressure in the reservoir constant when the blood suction is used.

RESULTS

The CPB-priming volume was significantly smaller in Group V (V vs. S: 1071+/-88 vs. 1405+/-137 ml; P<0.01), resulting in the lower hemodilution in Group V evidenced by the minimum hemoglobin level (V vs. S: 6.83+/-1.06 vs. 5.78+/-0.79 mg/dl; P<0.01) and blood transfusion rate (V vs. S: 9 vs. 20%; P<0.01). There were no significant differences in the plasma free hemoglobin level and the reduction ratio of plasma haptoglobin between the groups.

CONCLUSIONS

These data demonstrate that this vacuum-assisted CPB can provide simplification of the CPB circuit, resulting in a smaller CPB-priming volume and lower hemodilution. This vacuum-assisted CPB may attenuate the negative effect of CPB by minimizing hemodilution and appears to be a useful modification to accomplish no blood-requiring open heart operations.

Attenuation of a field Sendai virus isolate through egg-passages is associated with an impediment of viral genome replication in mouse respiratory cells

We investigated the mechanisms responsible for attenuation of mouse pathogenicity of Sendai virus (SeV) through passages in eggs. A highly virulent clone, E0, derived from the field SeV Hamamatsu strain, was successively passaged in hen's eggs. Analysis of the mouse lethal dose 50% (MLD50) of virus clones obtained from the viruses at egg-passages 1, 15, 30 and 50 demonstrated that attenuation of E0 by egg-passage occurred due to the gradual appearance of and replacement by virus variants possessing higher MLD50. Comparison of viral replication in the mouse lung and mouse pathogenicity with the representative SeV clones, E0, E15c12, E30c12 and E50c19, obtained from the respective egg-passages revealed that the low pathogenicity of the egg-passaged clones was due to poor multi-cycle viral replication in the lung. Furthermore, MLD50s of the SeV clones were found to be negatively correlated with the replication capability in primary mouse pulmonary epithelial (MPE) cells; the egg-passaged clones with more attenuated phenotypes showed lower replication capability in MPE cells. In the MPE cells infected with the SeV clones at m.o.i. 10, however, viral protein and mRNA syntheses of the egg-passaged clones were enhanced or comparable to those of the parental E0 clone at 1 day and 2 days post infection (p.i.) but decreased more rapidly thereafter. In contrast, viral genome synthesis of the egg-passaged clones in the cells at 2 days p.i. was several times lower than that of E0. These results strongly suggest that attenuation of a virulent field SeV strain by egg-passage occurs due to the appearance and selection of virus variants possessing poor propagation capacity in mouse respiratory epithelial cells, which is caused primarily by an impediment of viral genome replication.

Human CC chemokine liver-expressed chemokine/CCL16 is a functional ligand for CCR1, CCR2 and CCR5, and constitutively expressed by hepatocytes

Liver-expressed chemokine (LEC)/CCL16 is a human CC chemokine selectively expressed in the liver. Here, we investigated its receptor usage by calcium mobilization and chemotactic assays using mouse L1.2 pre-B cell lines stably expressing a panel of 12 human chemokine receptors. At relatively high concentrations, LEC induced calcium mobilization and chemotaxis via CCR1 and CCR2. LEC also induced calcium mobilization, but marginal chemotaxis via CCR5. Consistently, LEC was found to bind to CCR1, CCR2 and CCR5 with relatively low affinities. The binding of LEC to CCR8 was much less significant. In spite of its binding to CCR5, LEC was unable to inhibit infection of an R5-type HIV-1 to activated human peripheral blood mononuclear cells even at high concentrations. In human liver sections, hepatocytes were strongly stained by anti-LEC antibody. HepG2, a human hepatocarcinoma cell line, was found to constitutively express LEC. LEC was also present in the plasma samples from healthy adult donors at relatively high concentrations (0.3--4 nM). Taken together, LEC is a new low-affinity functional ligand for CCR1, CCR2 and CCR5, and is constitutively expressed by liver parenchymal cells. The presence of LEC in normal plasma at relatively high concentrations may modulate inflammatory responses.

Measurement of the midrapidity transverse energy distribution from square root of [(s)NN] = 130 GeV Au + Au collisions at RHIC

The first measurement of energy produced transverse to the beam direction at the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory is presented. The midrapidity transverse energy density per participating nucleon rises steadily with the number of participants, closely paralleling the rise in charged-particle density, such that <E(T)>/<N(ch)> remains relatively constant as a function of centrality. The energy density calculated via Bjorken's prescription for the 2% most central Au+Au collisions at square root[s(NN)] = 130 GeV is at least epsilon(Bj) = 4.6 GeV/fm(3), which is a factor of 1.6 larger than found at sqrt[s(NN)] = 17.2 GeV ( Pb+Pb at CERN).

NF-kappa B decoy suppresses cytokine expression and thermal hyperalgesia in a rat neuropathic pain model

Pro-inflammatory cytokines have been shown to be involved in the genesis, persistence, and severity of neuropathic pain following nerve injury. The transcription factor, nuclear factor-kappa B (NF-kappaB), plays a pivotal role in regulating pro-inflammatory cytokine gene expression. To elucidate the role of NF-kappaB in the pathogenesis of neuropathic pain, using a gene-based approach of NF-kappaB decoy, we tested whether the activated NF-kappaB affected pain behavior via the expression of inflammatory mediators. Single endoneurial injections of NF-kappaB decoy, at the site of nerve lesion, significantly alleviated thermal hyperalgesia for up to 2 weeks and suppressed the expression of mRNA of the inflammatory cytokines, iNOS, and adhesion molecules at the site of nerve injury. This finding suggests that a perineural inflammatory cascade, that involves NF-kappaB, is involved in the pathogenesis of neuropathic pain.

Expression of p73 in colorectal carcinoma: clinicopathological relevance

p73 gene expression and its correlation with clinicopathological variables were examined in 92 patients (53 male, 39 female; age range 38 - 89 years) with colorectal carcinoma. Gene expression was determined by immunohistochemical analysis of resected formalin-fixed and paraffin-embedded carcinoma specimens. When p73 staining of each specimen was divided into two modes (small expression, 0-50% and large expression, > 50%), small expression of p73 was obtained in most cases. Tumour, grade, stage, site and size did not correlate with the mode of expression, but tumour recurrence differed according to mode. Expression of p73 was also related to prognosis: large expression indicated a shorter survival period. Our findings suggest that p73 expression plays a role in inducing tumour recurrence, and that analysis of the expression is useful in evaluating the clinical course of colorectal carcinoma post-surgery.

Expression of zebrafish btg-b, an anti-proliferative cofactor, during early embryogenesis

BTG/tob family proteins are thought to be a potential tumor suppressor due to their anti-proliferative activity. We cloned zebrafish btg-b, a member of the BTG1/2 subfamily, using in situ hybridization screening. The tissue-specific expression of btg-b is first observed in the organizer region at the early gastrula stage. Later in development, the forebrain, the hindbrain, the polster and the paraxial mesoderm transiently express btg-b. Recently, mouse Btg1 and Btg2 have been shown to be a cofactor for Hoxb9. Double in situ hybridization with zebrafish btg-b and hoxb9a indicates that the expression domains of these two genes overlap in the posterior paraxial mesoderm.

Measurements of LET-distribution, dose equivalent and quality factor with the RRMD-III on the Space Shuttle Missions STS-84, -89 and -91

Dosimetric measurements on the Space Shuttle Missions STS-84, -89 and -91 have been made by the real-time radiation monitoring device III (RRMD-III). Simultaneously, another dosimetry measurement was made by the Dosimetry Telescope (DOSTEL) on STS-84 and by the tissue-equivalent proportional counter (TEPC) on STS-91. First, the RRMD-III instrument is described in detail and its results summarized. Then, the results of DOSTEL and TEPC are compared with those of the RRMD-III. Also, the absorbed doses obtained by TLD (Mg2SiO4) and by RRMD-III on board STS-84 and -91 are compared.

Impact of repeat hepatectomy on recurrent colorectal liver metastases

BACKGROUND

Hepatic recurrence is seen in approximately 40% of patients undergoing hepatectomy for colorectal metastases. This study was designed to assess the risks and clinical benefits of repeat hepatectomy for those patients.

METHODS

Twenty-six patients underwent repeat hepatectomy for hepatic recurrence, and their clinical data were retrospectively reviewed for operative morbidity and mortality, performance level, and survival.

RESULTS

There was no operative mortality after repeat hepatectomy. Operative bleeding was significantly increased in the second hepatectomy; but operating time, duration of hospital stay, and performance status after the second hepatectomy were comparable with those of the initial hepatectomy. The median survival time from the second hepatectomy was 31 months, and the 3- and 5-year survival rates were 62% and 32%, respectively. A short disease-free interval (6 months or less) between the initial hepatectomy and diagnosis of hepatic recurrence in the remnant liver was significantly associated with poor survival after the second hepatectomy.

CONCLUSIONS

Repeat resection contributed to clinical benefits for selected patients with hepatic recurrence after the initial hepatectomy for colorectal liver metastases. However, appearance of hepatic recurrence within 6 months or less after the initial hepatectomy is a poor prognostic factor for repeat hepatectomy.

Differential diagnosis of small round cervical lymph nodes: comparison of power Doppler US with contrast-enhanced CT and pathologic results

PURPOSE

The purpose of this study was to differentiate reactive small round lymph nodes (SRLNs) from metastases by power Doppler ultrasonography (PD-US) and contrast-enhanced CT (CE-CT).

MATERIALS AND METHODS

Both PD-US and CE-CT were performed in 99 cervical lymph nodes (LNs) with a maximum diameter of 1.5 cm or smaller and maximum longitudinal/transverse ratio of 1.5 or smaller in 76 patients with head and neck cancer. At pathologic examinations, 45 were reactive and 54 were metastatic LNs. The vascular patterns on PD-US were classified as hilar, avascular, peripheral, and miscellaneous vascular patterns. The enhancement patterns on CE-CT were classified as homogeneous, heterogeneous, and ring enhancement.

RESULTS

On PD-US, the hilar pattern was more frequently associated with benignancy (91%) and the peripheral, miscellaneous vascular pattern with malignancy (91%). The avascular pattern included both benign (58%) and malignant (42%) LNs. On PD-US, accuracy was 85%. On CE-CT, ring enhancement showed metastasis (100%), and these LNs showed avascular or peripheral patterns on PD-US. On CE-CT, accuracy was 77%. When information on CE-CT results was added to PD-US results, the accuracy rate increased significantly, to 94% (p=0.01).

CONCLUSION

Vascular patterns evaluated with PD-US and enhancement patterns on CE-CT can characterize SRLNs. For an avascular pattern on PD-US, information on CE-CT results can significantly increase the accuracy of characterization.

Centrality dependence of charged particle multiplicity in Au-Au collisions at square root of (s)NN = 130 GeV

We present results for the charged-particle multiplicity distribution at midrapidity in Au-Au collisions at square root of [s(NN)] = 130 GeV measured with the PHENIX detector at RHIC. For the 5% most central collisions we find dN(ch)/d eta(vertical line eta = 0) = 622+/-1(stat)+/-41(syst). The results, analyzed as a function of centrality, show a steady rise of the particle density per participating nucleon with centrality.

Impact of repeat hepatectomy on recurrent colorectal liver metastases

BACKGROUND

Hepatic recurrence is seen in approximately 40% of patients undergoing hepatectomy for colorectal metastases. This study was designed to assess the risks and clinical benefits of repeat hepatectomy for those patients.

METHODS

Twenty-six patients underwent repeat hepatectomy for hepatic recurrence, and their clinical data were retrospectively reviewed for operative morbidity and mortality, performance level, and survival.

RESULTS

There was no operative mortality after repeat hepatectomy. Operative bleeding was significantly increased in the second hepatectomy; but operating time, duration of hospital stay, and performance status after the second hepatectomy were comparable with those of the initial hepatectomy. The median survival time from the second hepatectomy was 31 months, and the 3- and 5-year survival rates were 62% and 32%, respectively. A short disease-free interval (6 months or less) between the initial hepatectomy and diagnosis of hepatic recurrence in the remnant liver was significantly associated with poor survival after the second hepatectomy.

CONCLUSIONS

Repeat resection contributed to clinical benefits for selected patients with hepatic recurrence after the initial hepatectomy for colorectal liver metastases. However, appearance of hepatic recurrence within 6 months or less after the initial hepatectomy is a poor prognostic factor for repeat hepatectomy.

Ultrasound activates the auditory cortex of profoundly deaf subjects

Using three-dimensional PET, the cortical areas activated by bone-conducted ultrasound were measured from five profoundly deaf subjects and compared with the cortical areas of normal-hearing subjects activated by stimuli through bone-conducted ultrasonic, air-conducted, bone-conducted, and vibro-tactile hearing aids. All of the hearing aids, including the ultrasonic hearing aid, consistently activated the medial portion of the primary auditory cortex of the normal volunteers. The same cortical area was also significantly activated in the profoundly deaf subjects although the percentage increase in regional cerebral blood flow (rCBF) was smaller than in normal subjects. These results suggest that extra-cochlear routes convey information to the primary auditory cortex and can therefore produce detectable sound sensation even in the profoundly deaf subjects, who reported a sensation themselves.

Lymphoepithelial cyst of the pancreas: report of a case

An extremely rare case of a lymphoepithelial cyst (LEC) of the pancreas is described herein. A pancreatic cystic tumor was initially detected in a 50-year-old man at a medical checkup. On admission, his serum carbohydrate antigen (CA) 19-9 level was 8100 U/ml and a computed tomography scan revealed a well-circumscribed multilocular cystic tumor in the pancreatic head and body. Magnetic resonance cholangiopancreatography showed no communication between the pancreatic ducts and the tumor. A distal pancreatectomy with lymph node dissection was performed because the lesion was suspected to be a mucinous cystadenoma or cystadenocarcinoma of the pancreas. However, histological examination revealed that the cyst was lined by stratified squamous epithelium and surrounded by lymphoid tissue. thereby confirming the diagnosis of LEC of the pancreas. The superficial layer of squamous epithelium and the cystic contents were found to be immunohistologically positive for CA19-9. Establishing a preoperative diagnosis of LEC is quite difficult because it resembles other cystic neoplasms of the pancreas in radiographic features and is frequently associated with an elevation of serum tumor markers such as CA19-9.

Portal vein thrombosis caused by microwave coagulation therapy for hepatocellular carcinoma: report of a case

Microwave coagulation therapy (MCT) is one of the treatment modalities for patients with hepatocellular carcinoma (HCC). A 67-year-old man with liver cirrhosis underwent MCT during a laparotomy for a deeply located HCC (2.5 cm in diameter) at the border of the anterior and posterior segments of the right hepatic lobe. Two weeks after MCT, he complained of abdominal fullness. Portal vein thrombosis (PVT) was diagnosed because he had massive ascites and an echogenic mass in the portal vein on abdominal ultrasonography. PVT was successfully treated by fibrinolytic therapy with a selective infusion of urokinase via the superior mesenteric artery (SMA). There have been few reports on PVT as a complication of MCT. Attention should be paid to the possible occurrence of PVT as a critical complication after MCT for liver tumors adjacent to the portal vein. Fibrinolytic therapy via the SMA is thus considered to be an effective approach for PVT after MCT.

Indication of splenectomy for gastric carcinoma involving the proximal part of the stomach

BACKGROUND/AIMS

The role of splenectomy in the surgical management of gastric carcinoma is controversial and there is no consensus of opinion regarding the therapeutic value of splenectomy. The aim of this study was to search for possible metastasis to lymph nodes in the splenic hilum or along the splenic artery to avoid unnecessary splenectomy and to determine its indication.

METHODOLOGY

The clinical records of 204 patients who underwent total gastrectomy combined with splenectomy for gastric carcinomas involving the proximal part of the stomach were analyzed.

RESULTS

The incidence of nodal involvement to the splenic hilum and/or along the splenic artery was 49 (24.0%) of 204 gastric carcinomas involving the proximal part of the stomach that underwent combined gastrectomy and splenectomy. The characteristics of gastric carcinoma with metastasis to these nodes included a larger tumor, deeper penetration (T3, 4 tumors), a number of lymph node metastasis, and infiltrative type. In T2 cases, all the tumors with cancerous involvement to these nodes showed intraoperative gross serosal change). When the tumor size was less than 40 mm, nodal metastatic rate to the splenic hilum and/or along the splenic artery was very low.

CONCLUSIONS

In conclusion, splenectomy should be conducted in T2 cases with gross serosal change and T3, 4 cases. With regard to tumor size, in the cases with a tumor whose size was less than 40 mm, it is possible to preserve the spleen in most cases. In the near future, splenectomy should be clarified precisely by randomized trials in advanced gastric carcinoma.

Intracystic hemorrhage of pancreatic serous cystadenoma after renal transplantation: report of a case

Immunosuppressive therapy after transplantation increases the risk of developing neoplasms, and neoplasms of the digestive organs are very common in Asia. We experienced a patient with an intracystic hemorrhage of pancreatic serous cystadenoma during the follow-up after renal transplantation. Pancreatic cystadenomas are not frequent. Only two cases, presenting with acute abdomen, have so far been reported in the literature. The intracystic hemorrhage in our case may have been related to a rapid tumor growth due to weakened antitumor immunity and azathioprine-induced pancreatitis.

Emergence of anti-inflammatory monocytes in long-term surviving hosts of IL-10-transduced liver allografts

We previously reported that transduction of IL-10 to rat liver allografts facilitates survival prolongation after orthotopic liver transplantation (OLT). In the current study, we examined Lewis hosts of IL-10-transduced allografts that had survived longer than 50 days in order to characterize peripheral blood mononuclear cells (PBMC). Phenotype analysis of the PBMC demonstrated an 18-fold increase in monocytes (CD11b/c(+)) with a massive increase in the monocyte/lymphocyte ratio. The monocytes expressed downregulated MHC class II (RT1B) but upregulated Fcgamma receptors in comparison with monocytes from the control hosts. The capacity of enriched monocytes to secrete TNF-alpha in response to LPS stimulation was downregulated in the survivors, while production of IL-10 was comparable. The monocytes from long-term survivors significantly inhibited the donor antigen stimulated secretion of IFN-gamma and IL-2. Monocytosis characterized by a shift to anti-inflammatory monocytes is associated with survival prolongation in the hosts of IL-10 transduced liver allografts.

A novel strategy of decoy transfection against nuclear factor-kappaB in myocardial preservation

BACKGROUND

Nuclear factor-kappaB (NFkappaB) is critical for the transcription of multiple genes involved in myocardial ischemia-reperfusion injury. Therefore, we hypothesized that blocking NFkappaB would attenuate ischemia-reperfusion injury after prolonged myocardial preservation, resulting in an improvement in cardiac function.

METHODS

Double-stranded oligodeoxynucleotides with a specific affinity for NFkappaB (NFkappaB decoy group) or a scrambled decoy group were transfected into rat hearts using a hemagglutinating virus of Japan-liposome method. After 16 hours of preservation in Euro-Collins solution at 4 degrees C, the cardiac grafts were heterotopically transplanted into recipient rats of the same strain.

RESULTS

Fluorescein isothiocyanate staining showed introduction of double-stranded oligonucleotides into the nuclei of endothelial cells and cardiomyocytes. After 1 hour of reperfusion the NFkappaB decoy group showed significantly higher degrees of recovery of left ventricular function as well as significantly lower levels of serum creatine phosphokinase, myocardial water content, tissue IL-8, and neutrophil infiltration than did the scrambled decoy group (p < 0.05).

CONCLUSIONS

Gene transfection of the NFkappaB decoy attenuates ischemia-reperfusion injury after prolonged heart preservation. As a result, this method appears to be a novel strategy for enhanced myocardial preservation.

Conserved and non-conserved regions in the Sendai virus genome: evolution of a gene possessing overlapping reading frames

We have sequenced the entire genome of a virulent field isolate of Sendai virus, the Hamamatsu strain, and compared the sequence with that of a distant related strain, the Z strain. Calculation of synonymous and non-synonymous (amino acid changing) nucleotide substitutions revealed regions where changes were permissive and non-permissive, and the experimentally determined functional region were found to be conserved, showing that important regions for function were conserved during evolution. In the cistron-overlapping regions in the P gene, one reading frame was conserved, whereas the other overlapping frame was flexible. The priority of one frame could be a strategy for evolution of an overlapping gene of RNA viruses. We found that the carboxyl two thirds of the C protein was conserved over the amino-terminal one third, possessing priority to the overlapping P polypeptide. This suggests that the carboxyl two thirds of the C protein have a functional importance. We also found a highly variable region between the L coding frame and the 5' trailer sequence. The relevance of these findings to actual viral replication should be clarified in the future.

Dissociation and recombination between ligands and heme in a CO-sensing transcriptional activator CooA. A flash photolysis study

CooA from Rhodospirillum rubrum is a transcriptional activator in which a heme prosthetic group acts as a CO sensor and regulates the activity of the protein. In this study, the electronic relaxation of the heme, and the concurrent recombination between ligands and the heme at approximately 280 K were examined in an effort to understand the environment around the heme and the dynamics of the ligands. Upon photoexcitation of the reduced CooA at 400 nm, electronic relaxation of the heme occurred with time constants of 0.8 and 1.7 ps. The ligand rebinding was substantially completed with a time constant of 6.5 ps, followed by a slow relaxation process with a time constant of 173 ps. In the case of CO-bound CooA, relaxation of the excited heme occurred with two time constants, 1.1 and 2.4 ps, which were largely similar to those with reduced CooA. The subsequent CO recombination process was remarkably fast compared with that of other CO-bound heme proteins. It was well described as a biphasic geminate recombination process with time constants of 78 ps (60%) and 386 ps (30%). About 10% of the excited heme remained unligated at 1.9 ns. The dynamics of rebinding of CO thus will help us to understand how the physiologically relevant diatomic molecule approaches the heme binding site in CooA with picosecond resolution.

[Vascular anastomoses in free jejunal reconstruction to the neck vessels: an experience of consecutive 20 cases without using surgical microscope]

Twenty consecutive cases of pharyngoesophageal cancer who underwent free jejunal reconstruction were reported. The common carotid or external carotid artery was used for a feeder of the free graft. The internal jugular vein were served as a drainage vein. All anastomoses were performed in an end-to-side fashion without using surgical microscopes. Mean carotid artery clamping time was 16 minutes and no neurological complications were noticed postoperatively. Graft failure was occurred in 1 patient. The presenting technique, showing 95% success rate, is recommended as a simple option for vascular anastomosis in free jejunal reconstructive surgery.

Accelerated growth signals and low tumor-infiltrating lymphocyte levels predict poor outcome in T4 esophageal squamous cell carcinoma

BACKGROUND

Little is known about the biological nature of T4 esophageal carcinoma growth signals and host defenses.

METHODS

Paraffin-embedded sections from 78 patients with T2 to T4 esophageal squamous cell carcinoma who underwent operation were analyzed with immunohistochemistry.

RESULTS

Positive cyclin A showed a significantly greater increase in T4 tumors than in those of other stages, and negative p27 showed a significantly greater decrease in T4 tumors than in large T3 stage tumors (tumor size > or = 4.0 cm). Patients with low-grade tumor-infiltrating lymphocyte (TIL) density showed a significantly greater decrease in T4 than in T2. The combination of p27 and cyclin A was a significant independent prognostic factor among T and N factors in multivariate analysis. TIL density was an independent prognostic factor among immunonutritional variables such as serum albumin concentration and the number of total blood lymphocytes.

CONCLUSIONS

T4 esophageal squamous cell carcinoma has a poor prognosis, which is associated with increased p27-negative and cyclin A-positive growth signals in the tumor and with low TIL density in the host.

Marginal ulceration after pylorus-preserving pancreaticoduodenectomy

Marginal ulceration is a serious problem after both standard pancreaticoduodenectomy (PD) and pylorus-preserving pancreaticoduodenectomy (PPPD). The relationship between this complication and the method of reconstruction after PPPD was analyzed in this study. Patients who underwent standard PD (n = 72) or PPPD (n = 28) in the 20-year period from 1978 to 1997 were retrospectively reviewed. After PPPD, 4 patients (14.3%) developed marginal ulceration on the jejunal side of the duodenojejunal anastomosis, while none of the patients had marginal ulceration after standard PD. The marginal ulcer occurred in 3 of 14 patients treated with the Roux-en-Y method, and in 1 of 9 treated with pancreatogastrostomy. In the Roux-en-Y method, the anal jejunal loop anastomosed to the bulb was directly exposed to gastric juice without neutralization by pancreatic juice from the oral jejunal limb. Of the 4 patients with marginal ulceration, 2 of those treated by the Roux-en-Y method required gastrectomy; the other 2 patients were treated medically. Our analysis of the literature showed that the Roux-en-Y method had the highest incidence of marginal ulcerations. The gastrointestinal reconstruction method without a mixture of gastric juice and pancreatic juice may be a causal factor in the marginal ulceration that occurs after PPPD. In reconstruction after PPPD, we should not create a jejunal loop that is exposed to gastric juice alone.

Is upper mediastinal lymphadenectomy necessary in squamous carcinoma of the lower thoracic oesophagus?

AIM

We examined the indication of upper mediastinal lymphadenectomy for a squamous cell carcinoma of the lower thoracic oesophagus.

METHODS

49 patients underwent a curative oesophagectomy with upper mediastinal lymphadenectomy for a squamous cell carcinoma of the lower thoracic oesophagus. Node status and clinicopathological characteristics of these patients were reviewed retrospectively.

RESULTS

16 (94.1%) of 17 patients with superficial tumours had no positive node in the upper mediastinum. Nine (29.0%) of 31 patients with transmural tumours had positive nodes in the upper mediastinum (P = 0.04). Ten (20.4%) of 49 patients had many positive nodes in the upper mediastinum. Of these 10 patients, 6 patients had 5 or more positive nodes in all. The 5-year survival rate for patients with 5 or more positive nodes was 7.7%, which was significantly poorer than patients with 4 or fewer positive nodes.

CONCLUSIONS

Upper mediastinal lymphadenectomy is unnecessary in most of the superficial squamous carcinomas of the lower thoracic oesophagus.

Predicting initial recurrence pattern of esophageal cancer after neoadjuvant chemotherapy

BACKGROUND/AIMS

No report has reviewed which clinicopathological factors including 3-field dissection and the response to neoadjuvant chemotherapy can predict the recurrence pattern of an esophageal carcinoma. The aim of this study was to reveal clinicopathological predictors for the initial recurrence pattern of a thoracic esophageal carcinoma.

METHODOLOGY

Sixteen parameters derived from 98 patients who underwent a curative esophagectomy with neoadjuvant chemotherapy for a squamous cell carcinoma of the thoracic esophagus were examined using univariate and multivariate logistic regression analyses.

RESULTS

Thirty-seven (37.8%) of the 98 patients had recurrences (hematogenous; 16, lymphatic; 13, others; 8). Univariate analyses revealed that the completion of 3-field dissection was the only factor for suppressing the lymphatic recurrence (P = 0.009; odds ratio: 0.2). Multivariate analyses showed that the number of positive nodes was a significant predictor for recurrence including all modalities (P = 0.02; odds ratio: 1.2) and both the number of positive nodes (P = 0.04; odds ratio: 1.1) and the poor response to neoadjuvant chemotherapy (P = 0.02; odds ratio: 6.9) were significant predictors for the hematogenous recurrence.

CONCLUSIONS

The number of positive nodes and the response to neoadjuvant chemotherapy could predict the hematogenous recurrence of esophageal carcinoma.

Recurrent nerve nodal involvement is associated with cervical nodal metastasis in thoracic esophageal carcinoma

BACKGROUND

Because three-field dissection for esophageal carcinoma is one of the most invasive operations, this procedure should be selected only when strictly indicated; but there are no useful criteria for it. The goal of this study was to identify the useful clinicopathologic factors for indicating three-field dissection.

STUDY DESIGN

In this study, we reviewed the survival of patients after three-field dissection and identified factors associated with metastases in cervical nodes (CN), especially internal jugular nodes and supraclavicular nodes. Eighty-six patients who underwent curative esophagectomy with three-field dissection for squamous cell carcinoma of the thoracic esophagus were enrolled in this study. Survival rates were compared with respect to the presence of nodal metastasis. The relationship between recurrent nerve nodal (RNN) involvement and CN metastasis (bilateral internal jugular nodes, supraclavicular nodes, or both) was examined. Clinicopathologic factors possibly influencing CN metastasis were studied by multivariate logistic regression analysis.

RESULTS

The overall 5-year survival rate was 45.1%. The 5-year survival rate for patients without metastatic nodes was 67.5%, for patients with one to four metastatic nodes it was 53.1%, and for patients with five or more it was 9.1 %. The prognosis of those with five or more metastatic nodes was significantly poorer than those of the other two groups. In the positive-node group, the 5-year survival rate for patients with RNN metastasis was 21.7%, and for patients with negative RNN it was 47.0% (p = 0.2). In the positive-node group, the 5-year survival rate for patients with positive CN was 13.7% and for patients with negative CN it was 45.8% (p = 0.01). Fifty-six (88.9%) of 63 patients without RNN metastasis had no CN metastasis in contrast to 13 of 23 patients (56.5%) with RNN metastasis who had no CN metastasis (p = 0.001). The positive predictive value, negative predictive value, sensitivity, and specificity were 43.5%, 88.8%, 58.8%, and 81.2%, respectively. The number of metastatic nodes (5 or more versus 0-4) (odds ratio: 2.9, 95% Confidence Interval (CI) = 1.6-5.5, p = 0.0008) and RNN involvement (odds ratio: 4.5, 95% CI = 1.3-15.9, p = 0.02) were the significant factors associated with CN metastasis in the multivariate analysis.

CONCLUSIONS

RNN involvement is associated with CN metastasis as is the number of metastatic nodes and may be an indicator for the selection of three-field dissection in thoracic esophageal carcinoma.

Involvement of the zinc-binding capacity of Sendai virus V protein in viral pathogenesis

The V protein of Sendai virus (SeV) is nonessential to virus replication in cell culture but indispensable to viral pathogenicity in mice. The highly conserved cysteine-rich zinc finger-like domain in its carboxyl terminus is believed to be responsible for this viral pathogenicity. In the present study, we showed that the cysteine-rich domain of the SeV V protein could actually bind zinc by using glutathione-S-transferase fusion proteins. When the seven conserved cysteine residues at positions 337, 341, 353, 355, 358, 362, and 365 were replaced individually, the zinc-binding capacities of the mutant proteins were greatly impaired, ranging from 22 to 68% of that of the wild type. We then recovered two mutant SeVs from cDNA, which have V-C(341)S and V-C(365)R mutations and represent maximal and minimal zinc-binding capacities among the corresponding mutant fusion proteins, respectively. The mutant viruses showed viral protein synthesis and growth patterns similar to those of wild-type SeV in cultured cells. However, the mutant viruses were strongly attenuated in mice in a way similar to that of SeV V(DeltaC), which has a truncated V protein lacking the cysteine-rich domain, by exhibiting earlier viral clearance from the mouse lung and less virulence to mice. We therefore conclude that the zinc-binding capacity of the V protein is involved in viral pathogenesis.

Abdomen, pelvis, and extremities: diagnostic accuracy of dynamic contrast-enhanced turbo MR angiography compared with conventional angiography-initial experience

To determine the value of contrast material-enhanced three-dimensional turbo magnetic resonance (MR) angiography compared with conventional cut-film or digital subtraction angiography for evaluating arterial stenosis in the abdomen, pelvis, and extremities. For detection of significant stenosis, MR angiography had 91% sensitivity and 89% specificity. This technique is highly sensitive in lesion detection, but stenosis tended to be overestimated.

[Surgical treatment of unruptured cerebral aneurysms and complications in patients with ischemic cerebrovascular disease]

Patients who have unruptured intracranial aneurysms associated with ischemic cerebrovascular disease are a high-risk group for surgery. We have done clipping surgery in 15 patients among 40 with ischemic cerebrovascular disease. The criteria for surgery included an age below 65 years, CBF of more than 35 ml/100 g/min, and favorable ADL comparable to Rankin score 0-III. Two patients received simultaneous aneurysm clipping and superficial-middle cerebral artery anastomosis. Only one patient suffered from ischemia-related permanent neurological worsening, and one had direct optic nerve injury. Surgical mortality was 0%, and morbidity was 15%. There were two patients who had transient neurological worsening. These results suggest that surgical treatment of unruptured cerebral aneurysms is not contraindicated in patients with ischemic brain disease, but careful selection and careful perioperative management are mandatory for preventing surgical complications.

Ecto-5'-nucleotidase plays a role in the cardioprotective effects of heat shock protein 72 in ischemia-reperfusion injury in rat hearts

OBJECTIVE

Heat shock protein 72 (HSP72) is involved in the myocardial self-preservation system under several conditions such as ischemia-reperfusion injury or late preconditioning. However, its mechanism is not fully understood. Ecto-5'-nucleotidase is a key enzyme for synthesizing adenosine and plays an important role in ischemic preconditioning. In this study, we tested the hypothesis that ecto-5'-nucleotidase plays a role in the cardioprotection of HSP72.

METHODS

Rat hearts (H group, n=6) were transfected with HSP72 gene by an intracoronary infusion of hemagglutinating virus of Japan (HVJ)-liposome complex. Control hearts (C group, n=6) were transfected with the beta-galactosidase gene. Following 30 min of normothermic ischemia, grafts were reperfused using Langendorff apparatus.

RESULTS

The activity of ecto-5'-nucleotidase was significantly higher in H group than C group both before and after ischemia-reperfusion (H vs. C; 0.51+/-0.05 vs. 0.29+/-0.06, and 1.41+/-0.15 vs. 0.85+/-0.11 nmol/mg protein/min, P<0.05). H group also showed significant better functional recoveries than C group (P<0.05), as well as less creatine phosphokinase leakage (4.4+/-2.8 vs. 14.2+/-3.4 mU/min, P<0.05) and higher adenosine release (247.5+/-35.1 vs. 54.3+/-1.7 pmol/min, P<0.05). Administration of alpha,beta-methylene adenosine diphosphate (AMP-CP), an inhibitor of ecto-5'-nucleotidase, significantly diminished the tolerance to ischemia-reperfusion injury in H group (P<0.05).

CONCLUSION

These results demonstrated that ecto-5'-nucleotidase activated by an overexpression of HSP72 attenuated ischemia-reperfusion injury in the rat myocardium. They suggest that ecto-5'-nucleotidase plays a role in the cardioprotective effects of HSP72 in rat hearts.

The roles of platelet-activating factor and endothelin-1 in renal damage after total hepatic ischemia and reperfusion

BACKGROUND

This study was designed to verify the involvement of platelet-activating factor (PAF) in renal damage associated with hepatic ischemia and reperfusion (HIR) injury through the release of endothelin (ET)-1 and to determine the modulating effect of a specific PAF receptor antagonist on these insults in rats.

METHODS

Male rats pretreated with either normal saline as a vehicle (NS group) or intravenous TCV-309, a PAF receptor antagonist (TCV group), were subjected to 120 min of total hepatic ischemia under an extracorporeal portosystemic shunt. Plasma aspartate transaminase, creatinine, blood urea nitrogen, and ET-1 levels and the relative renal wet weight were determined under nonischemic conditions and at 1, 3, and 6 hr of reperfusion after hepatic ischemia. Changes in mean arterial blood pressure and renal tissue blood flow measurements in the kidney were determined throughout the experiment.

RESULTS

Increased plasma aspartate transaminase, creatinine, blood urea nitrogen, and ET-1 levels and the relative renal wet weight after HIR in the NS group were significantly suppressed by TCV-309 pretreatment. Mean arterial blood pressure and renal tissue blood flow after HIR in the TCV group were significantly improved when compared with those in the NS group. These effects resulted in attenuation of structural hepatic and renal damage with the improvement of 7-day survival (62%).

CONCLUSIONS

The present study demonstrates that renal damage as well as critical liver injury is produced after reperfusion following 120 min of total hepatic ischemia. A PAF receptor antagonist may be therapeutically useful to protect against these types of damage via indirect modulation of plasma ET-1 levels.

Claudins regulate the intestinal barrier in response to immune mediators

BACKGROUND & AIMS

To determine the functional role of immune mediators in the formation of the intestinal barrier, we have examined the regulation of claudin expression by interleukin (IL)-17 in human intestinal epithelial cells.

METHODS

Expression of claudins, extracellular signal-related (ERK) mitogen-activated protein kinases (MAPKs), and activated ERK MAPKs was determined by immunoblotting. Claudin membrane association was assessed by immunohistochemistry and claudin messenger RNA expression by Northern blot analysis. Intestinal epithelial barrier function was characterized through transepithelial electrical resistance and mannitol tracer flux.

RESULTS

IL-17 induced the development of a paracellular barrier of T84 cell monolayers. Inhibition of ERK activation with the MEK inhibitor PD98059 blocked IL-17 as well as basal development of tight junctions in T84 cells. IL-17 induced formation of tight junctions correlated with up-regulation of claudin-1 and claudin-2 gene transcription. Inhibition of MEK reduced the activated and basal expression of claudin-2 messenger RNA and protein expression. Functional MEK was required for the expression and membrane association of claudin-2 but not claudin-1 in T84 cells.

CONCLUSIONS

MEK activity is required for claudin-mediated formation of tight junctions. IL-17 is able to regulate the intestinal barrier through the ERK MAPK pathway.

[Availability of antibacterial towels and fabrics against enterohemorrhagic Escherichia coli]

OBJECTS

After outbreaks of enterohemorrhagic Escherichia coli, various varieties of antibacterial kitchen and table materials are being used in Japan. The actual of availability of towels and fabrics, designated as antibacteria, against enterohemorrhagic E. coli was evaluated.

METHODS

For an indicator strain a clinically isolated strain of E. coli O157:H7 C2 in Canada was utilized. Material kept in a tube was autoclaved at 121 degrees C for 15 mins, and 200 microliters of the bacterial culture was inoculated on the material, and cultured at 35 degrees C for an adequate interval. Colony forming units (CFU) of the materials were estimated. We also studied bactericidal effects of copper-fixed towels after washing. Materials without antibacterial processing or white cotton towels were used as controls.

RESULTS

CFU of E. coli on silver- or copper-fixed materials at 18 hrs after inoculation were markedly decreased, compared to CFU of bacteria on the controls at 0 hr after inoculation. These materials were found to have bactericidal activity. Three materials of 23 samples were found to have bacterial inhibitory activity, because CFU of bacteria on the 3 materials at 18 hrs after inoculation were less than CFU of bacteria on the controls at 18 hrs. Thirteen materials (56.5%) were found to have no evident bactericidal nor inhibitory activity. CFU of silver- or copper-fixed materials were clearly decreased at 3 hrs and 20 mins after inoculation, respectively. It was also recognized that bactericidal activity was sustained at 18 hrs after inoculation even after the copper-fixed towel was washed 50 times.

CONCLUSION

Evaluation of bactericidal effects of towels and fabrics, that claim to be antibacterial, showed that a few materials had bactericidal or inhibitory activity. Consumers must not have too much confidence in claims of a product being antibacteria. Even if antibacterial materials are available, the most important measure for us is to wash sufficiently and maintain sanitary conditions.

Percutaneous cardiopulmonary support with heparin-coated circuits in postcardiotomy cardiogenic shock. Efficacy and comparison with left heart bypass

OBJECTIVE

Percutaneous cardiopulmonary support, a simplified form of venoarterial bypass, using totally heparin-coated circuits, has recently come into clinical use. To clarify its efficacy in postcardiotomy cardiogenic shock to aid weaning from cardiopulmonary bypass, we compared results of percutaneous cardiopulmonary support with those of left heart bypass using a centrifugal pump.

METHODS

We reviewed 18 patients treated between 1991 and 1998 who could not be weaned from cardiopulmonary bypass. Nine were aided by totally heparin-coated percutaneous cardiopulmonary support (PCPS group), and 9 supported by left heart bypass using a centrifugal pump (LHB group). In both groups, activated clotting time was controlled at 150-200 seconds using minimal doses of heparin as needed.

RESULTS

Weaning and survival rates were higher in the PCPS group than in the LHB group (100% vs 55.6%, and 66.7% vs 22.2%). The PCPS group had a smaller amount of blood loss and needed a smaller amount of blood components in the immediate postoperative period. One percutaneous cardiopulmonary support patient required surgical re-exploration for postoperative bleeding (11.1%), but no clinical thromboembolic event occurred in the PCPS group. In the LHB group, 5 patients underwent surgical re-exploration for postoperative bleeding (55.6%), and 2 underwent thrombus extirpation in the left ventricle (22.2%).

CONCLUSIONS

Although this study was retrospective and historical backgrounds could have been involved, our data suggest that totally heparin-coated percutaneous cardiopulmonary support system appears more effective as an aid to weaning from cardiopulmonary bypass and in short-term circulatory support for patients in postcardiotomy cardiogenic shock.

Hepatectomy for hepatocellular carcinoma in a renal transplant patient--report of a case and literature review

A 45-year-old woman underwent hepatectomy for hepatocellular carcinoma developing after 2 renal transplants. She had a solitary hepatocellular carcinoma and central bisegmentectomy of the liver was performed. Administration of immunosuppressants was continued to maintain renal function in the perioperative period. Although our patient suffered from severe pneumonia postoperatively, she recovered without a decline in renal function. She has been alive for 1 year and 3 months after hepatectomy with hepatocellular carcinoma recurrence in the remnant liver. Any patient undergoing hepatectomy for hepatocellular carcinoma after renal transplantation should be managed as an immunocompromised host. Previously reported cases of hepatectomy for hepatocellular carcinoma in renal transplant recipients were reviewed.

Early experience of aortic valve replacement with the Freestyle stentless aortic bioprosthesis in elderly patients

OBJECTIVES

Stentless bioprostheses have been gaining popularity in recent years as hemodynamically superior alternatives to conventional stented bioprostheses.

METHODS

Between July 1996 and November 1998, 13 patients with aortic valve disease, 7 males and 6 females with a mean age (+/- SD) of 68 +/- 5 years, underwent an aortic valve replacement using the Medtronic Freestyle aortic bioprosthesis. The predominant lesions were stenosis in 8 patients and regurgitation in 5, while 2 patients had endocarditis. The operation was performed by a subcoronary technique in 9, root-inclusion technique in 3, and full root technique in 1 patient.

RESULTS

Throughout the follow-up periods (with average follow-up period of 20.6 months), there was no hospital mortality, though there was one late death of unknown cause. The New York Heart Association class improved in all patients. The peak transvalvular gradient decreased from 18.4 +/- 9.8 to 12.6 +/- 9.6 mmHg, and the effective valve orifice area increased from 2.30 +/- 0.96 to 2.59 +/- 1.05 cm2 between the 1-month and the 6-month follow-up examinations. In patients with aortic regurgitation, the left ventricular end-diastolic/end-systolic volume index significantly decreased from 147 +/- 36/62 +/- 19 to 73 +/- 26/33 +/- 14 ml/m2 at 1 month after the operation. The left ventricular mass index also significantly decreased from 189 +/- 26 to 143 +/- 30 g/m2 in patients with aortic regurgitation and from 171 +/- 28 to 144 +/- 30 g/m2 in those with aortic stenosis.

CONCLUSIONS

Although long-term follow-up is required for further evaluation, the early results appeared to indicate that the Freestyle aortic bioprosthesis was suitable for elderly patients requiring aortic valve replacement.

Molecular mechanism of magnet formation in bacteria

Magnetic bacteria have an ability to synthesize intracellular ferromagnetic crystalline particles consisting of magnetite (Fe3O4) or greigite (Fe3S4) which occur within a specific size range (50-100 nm). Bacterial magnetic particles (BMPs) can be distinguished by the regular morphology and the presence of an thin organic membrane enveloping crystals from abiologically formed magnetite. The particle is the smallest magnetic crystal that has a regular morphology within the single domain size. Therefore, BMPs have an unfathomable amount of potential value for various technological applications not only scientific interests. However, the molecular and genetic mechanism of magnetite biomineralization is hardly understood although iron oxide formation occurs widely in many higher animals as well as microorganisms. In order to elucidate the molecular and genetic mechanisms of magnetite biomineralization, a magnetic bacterium Magnetospirillum sp. AMB-1, for which gene transfer and transposon mutagenesis techniques had been recently developed, has been used as a model organism. Several findings and information on the BMPs formation process have been obtained within this decade by means of studies with this model organism and its related one. Biomineralization mechanism and potential availability in biotechnology of bacterial magnets have been elucidated through molecular and genetic approach.

Application of real-time radiation dosimetry using a new silicon LET sensor

A new type of real-time radiation monitoring device, RRMD-III, consisting of three double-sided silicon strip detectors (DSSDs), has been developed and tested on-board the Space Shuttle mission STS-84. The test succeeded in measuring the linear energy transfer (LET) distribution over the range of 0.2 keV/micrometer to 600 keV/micrometer for 178 h. The Shuttle cruised at an altitude of 300 to 400 km and an inclination angle of 51.6 degrees for 221.3 h, which is equivalent to the International Space Station orbit. The LET distribution obtained for particles was investigated by separating it into galactic cosmic ray (GCR) particles and trapped particles in the South Atlantic Anomaly (SAA) region. The result shows that the contribution in dose-equivalent due to GCR particles is almost equal to that from trapped particles. The total absorbed dose rate during the mission was 0.611 mGy/day; the effective quality factor, 1.64; and the dose equivalent rate, 0.998 mSv/day. The average absorbed dose rates are 0.158 mGy/min for GCR particles and 3.67 mGy/min for trapped particles. The effective quality factors are 2.48 for GCR particles and 1.19 for trapped particles. The absorbed doses obtained by the RRMD-III and a conventional method using TLD (Mg(2)SiO(4)), which was placed around the RRMD-III were compared. It was found that the TLDs showed a lower efficiency, just 58% of absorbed dose registered by the RRMD-III.

Disparity of cell swelling and rapid neuronal death by excitotoxic insults in rat hippocampal slice cultures

The rapidly (< 1 h) developing neuronal death induced by a 15-min-exposure to N-methyl-D-aspartate (NMDA) in rat hippocampal slice cultures is associated with cell swelling. We examined whether the swelling directly leads to neuronal death. The rapid neuronal death assayed by propidium iodide was Cl(-)-dependent, as reported for the cell swelling. However, the dose-dependence for NMDA-induced neuronal death differed from that for the cell swelling. Also, cell swelling alone induced by hypotonic insults led to neuronal death only when the cell size increased far more than the extent achieved by NMDA insults. Moreover, contrary to the previous notion, the rapid neuronal death was Ca2+-dependent. Thus, the primary cause of the rapid neuronal death induced by NMDA cannot be attributed to cell swelling.

Double-layered membrane vesicles released from mammalian cells infected with Sendai virus expressing the matrix protein of vesicular stomatitis virus

The matrix (M) protein of vesicular stomatitis virus (VSV) was reported to form vesicles on the cell surface and subsequently to be released into the cultured medium when expressed from cDNA by virus vectors. To further investigate VSV M activity, we generated a recombinant Sendai virus (SeV) expressing the VSV M protein (SeV-M(VSV)). When cells were infected with SeV-M(VSV), VSV M was found abundantly in the culture medium. Electron microscopy demonstrated the budding of two-membraned vesicles (>/= 0.8 microm in diameter) from the infected cells. The outer membrane of the vesicle was derived from the plasma membrane and the inner one possibly derived from the membrane of an intracellular vesicle. Immuno-gold labeling showed that VSV M was exclusively located in a double-layered region. The released membranes were divided into three parts: the VSV M vesicles with SeV F and HN glycoproteins, SeV particles, and vesicles associated with the cytosolic components. The last abundantly contained phosphorylated SeV matrix (M) protein, which is not released in a usual SeV infection. Furthermore the VSV M protein expressed without using a virus vector was efficiently released into the culture medium. These results suggest that the VSV M protein has a budding activity per se and that SeV proteins are passively involved in the release of VSV M.