Cyclic-AMP inhibits nitric oxide-induced apoptosis in human osteoblast: the regulation of caspase-3, -6, -9 and the release of cytochrome c in nitric oxide-induced apoptosis by cAMP

Nitric oxide (NO) induces apoptotic cell death and cAMP has a significantly protective effect on NO-induced cytotoxicity in human osteoblasts, MG-63 cells. Treatment with S-nitroso-N-acetylpenicillamine (SNAP) (0.6 mM) resulted in genomic DNA fragmentation, characteristic of apoptosis. However, concomitant incubation of the cells with either DBcAMP or forskolin markedly inhibited SNAP-induced apoptosis in a dose-dependent manner. Furthermore, pretreatment of MG-63 cells with H-89 or KT5720, which is known to inhibit cAMP-dependent protein kinase (PKA), abolished the protective effect of DBcAMP and forskolin on SNAP-induced apoptosis. In this study, we explored the involvement of caspases in the regulatory mechanism of SNAP-induced apoptosis by cAMP. Our data show that DBcAMP or forskolin blocked SNAP-induced caspase-3-like cysteine protease activation and that H-89, a PKA inhibitor, reversed the cAMP-induced regulatory effect of caspase-3 like protease. Consistent with the results, cAMP inhibited the proteolytic cleavage of caspase-3, -6, -9 and cytochrome c release to cytoplasm. The inhibition of caspase-3 activation did not block SNAP-induced cytochrome c release to cytoplasm, suggesting that caspase-3 activation may occur downstream of cytochrome c release. In summary, these findings show that the exposure of MG-63 cells to cAMP analogs renders them more resistant to NO-induced damage and suggests the presence of regulatory mechanisms of the cell death pathway by cAMP in which caspase-3, -6, and -9 and cytochrome c release serves to mediate NO-induced apoptosis.

Optical peroxide biosensor using the electrically controlled-release technique

An optical biosensor using an electrically controlled-release system was developed for the measurement of peroxide concentration. The electrically controlled-release system consisted of a current-supplying system and a polymer complex by hydrogen bonding between the carboxylic and oxazoline group. The polymer complex was formed below pH 5.0 and was degraded above pH 5.4. The local pH change near the surface of the polymer complex could be controlled by applying the electric current to release an enzyme reaction reagent, 4-hydroxyphenylacetic acid (HPA), in the polymer complex. The releasing rate of HPA was proportional to the electric current applied to the polymer complex. The model of the controlled-release system was proposed to predict the degradation velocity of the polymer complex, which is equivalent to the releasing rate of HPA. The released HPA and analyte, peroxide, flowed into the reactor with the immobilized enzyme and then reacted with the enzyme. The peroxide concentration was measured based on the fluorescence detection of enzyme reaction product, 6,6'-dihydroxy (1,1'-biphenyl) 3,3'-diacetic acid (DBDA). The proposed biosensor had the linear analytical range of 0.025 approximately 1.0 mM with a response time of 20 min, good repeatability, and reproducibility.

Hypoxia induces apoptosis by caspase activation accompanying cytochrome C release from mitochondria in MC3T3E1 osteoblasts. p38 MAPK is related in hypoxia-induced apoptosis

The aim of this study is to elucidate the possible mechanism of apoptosis in response to hypoxia in MC3T3E1 osteoblasts. MC3T3E1 osteoblasts under hypoxic conditions (2% oxygen) resulted in apoptosis in a time-dependent manner estimated by DNA fragmentation assay and nuclear morphologystained with fluorescent dye, Hoechst 33258. Pretreatment with Z-VAD-FMK, a pan-caspase inhibitor, or Z-DEVD-CHO, a specific caspase-3 inhibitor, completely suppressed the DNA ladder in response to hypoxia. An increase in caspase-3-like protease (DEVDase) activity was observed during apoptosis, but no caspase- activity (YVADase) was detected. To confirm what caspases are involved in apoptosis, western blot analysis was performed using anti-caspase-3 or -6 antibody. The 10-kDa protein, corresponding to the active products of caspase-3 and the 10-kDA protein of the active protein of caspase-6 were generated in hypoxia-challenged cells in which processing of the full length form of caspase-3 and -6 was evident. With a time course similar to this caspase-3 and -6 activation was evident, hypoxic stress caused the cleavage of lamin A, typical of caspase-6 activity. In addition, the stress elicited the release of cytochrome c into the cytosol during apoptosis. Furthermore, we have observed that pre-treatment with SB203580, a selective p38 MAP kinase (p38 MAPK) inhibitor, attenuated the hypoxia-induced apoptosis. The addition of SB203580 suppressed caspase-3 and -6-like protease activity by hypoxia up to 50%. In contrast, PD98059 had no effect on the hypoxia-induced apoptosis. To confirm the involvement of MAP kinase, JNK/SAPK, ERK, or p38 kinase assay was performed. Although p38 MAPK was activated in response to hypoxic treatment, the other MAP kinase -JNK/SAPK or ERK- was not or modestly activated. These results suggest that p38 MAPK positively regulates hypoxia-induced apoptosis in MC3T3E1 osteoblasts.

New experiences with absolute ethanol sclerotherapy in the management of a complex form of congenital venous malformation

BACKGROUND

Complex forms of congenital venous malformation have defied proper classification and confounded therapy. Through a newly designed multidisciplinary approach, these venous defects were properly diagnosed and classified according to the Hamburg classification. Absolute ethanol was adopted as a new scleroagent for this complex form of venous defects to improve overall treatment results with acceptable morbidity and recurrence rates.

PATIENTS AND METHODS

Among 318 patients aged 2 months to 60 years (130 men: mean age, 24.6 years; 188 women: mean age, 24.5 years), 143 patients were confirmed as having venous defects predominantly (45%). We conducted diagnostic evaluation with magnetic resonance imaging, whole body blood pool scan, duplex scans, transarterial microalbumin lung scans, air plethysmography, bone x-ray film, and angiography. Thirty of 143 patients were indicated for the absolute ethanol sclerotherapy for the complex form of venous defects, and they completed 98 sessions of multistage therapy with direct puncture technique. Follow-up assessment (minimum, 6 months; average, 10.2 months) was made as early results after completion of therapy.

RESULTS

The immediate success rate at the completion of treatment through 98 sessions on 30 patients was 92% (90/98). The reason for the failure of 8% (8/98 sessions) was mainly due to the lesion's inaccessibility to the nidus to deliver the alcohol safely. On follow-up assessment available on 28 of 30 patients, overall improvement of the lesions with good to fair response on clinical assessment was obtained in 27 (96%) of 28 patients. Similar good to fair responses were obtained on whole body blood pool scan assessment (14 [93%] of 15 patients) and also on magnetic resonance imaging assessment (12 [93%] of 13 patients). Various major to minor acute complications developed during the procedure in eight (26.7%) of 30 patients through 16 (16.3%) of 98 sessions of the therapy: ischemic bullae, tissue fibrosis, deep venous thrombosis, pulmonary embolism, peripheral nerve palsy, and temporary pulmonary hypertension. All 24 incidences of complication were successfully managed with full recovery except one case of permanent peroneal nerve palsy that was present during 18 months of follow-up. No single recurrence has been detected to date.

CONCLUSION

Absolute ethanol sclerotherapy alone can deliver excellent results in complex forms of venous malformations with considerable but acceptable morbidity and may be able to reduce the morbidity involved with the conventional surgical therapy alone on complex forms of venous malformation. No recurrence or deterioration of the therapy results was observed during the follow-up period (average, 10.2 months) after the completion of multistaged therapy.

Characterization of mouse brain-specific angiogenesis inhibitor 1 (BAI1) and phytanoyl-CoA alpha-hydroxylase-associated protein 1, a novel BAI1-binding protein

Previously, PAHX-AP1 (PAHX-associated protein 1) was isolated as a novel protein to interact with Refsum disease gene product (phytanoyl-CoA alpha-hydroxylase, PAHX) and specifically expressed in mouse brain. PAHX-AP1 is also suggested to be involved in the development of the central neurologic deficits of Refsum disease. To clarify its function, we have searched for proteins that associate with PAHX-AP1 via yeast two-hybrid system. We found that PAHX-AP1 interacts with the cytoplasmic region of human brain-specific angiogenesis inhibitor 1 (hBAI1), and isolated murine homolog of hBAI1. Structural analysis of the PAHX-AP1 with three reported hBAI-associated proteins (BAP) revealed no homology among them, and we designated PAHX-AP1 as BAP4. The ability of BAP4 to interact with BAI1 was confirmed by pulling-down BAI1 with GST-BAP4 protein and immunoprecipitation study using brain lysate. Northern and Western blot analyses demonstrated a unique pattern of BAI1 expression in the brain. The peak level of BAI1 was observed 10 days after birth. In situ hybridization analyses of the brain showed the same localization of BAI1 as BAP4, such as most neurons of cerebral cortex, hippocampus, and V, VI, VII, VIII, and XII nuclei. Because BAI1 possessed thrombospondin-type 1 repeats in its extracellular region, changes of BAI1 expression were examined in the focal cerebral ischemia model. The BAI1 expression decreased on the ischemic side after 24 h but BAP4 was not changed after the time-course of ischemia. Our results indicate that expression and localization of BAI1 in the brain is correlated with BAP4, and that BAI1 is involved in inhibition of angiogenesis and neuronal differentiation.

Blockade of the p38 mitogen-activated protein kinase pathway inhibits inducible nitric oxide synthase and interleukin-6 expression in MC3T3E-1 osteoblasts

Treatment of MC3T3E-1 osteoblast cultures with combined interferon- gamma(IFN- gamma), lipopolysaccharide (LPS) and tumor necrosis factor- alpha(TNF- alpha) induces expressions of inducible nitric oxide synthase (iNOS) and interleukin-6 (IL-6), resulting in sustained releases of large amounts of nitric oxide and IL-6. However IFN- gamma, LPS and TNF- alpha individually induces non-detectable or small amounts of NO and IL-6 in MC3T3E-1 osteoblasts. The role of mitogen-activated protein kinase (MAPK) activation in the early intracellular signal transduction involved in iNOS and IL-6 transcription in the combined agents-stimulated osteoblasts has been investigated. The p38 MAPK pathway is specifically involved in the combined agents-induced NO and IL-6 release, since NO and IL-6 release in the presence of a specific inhibitor of p38 MAPK, 4-(4-fluorophenyl)-2-(4-metylsulfinylphenyl)-5-(4-pyridyl)imidazole (SB203580), are significantly diminished. In contrast, PD98059, a specific inhibitor of MEK1, had no effect on NO and IL-6 release. Northern blot analysis showed that the p38 MAPK pathway controlled iNOS and IL-6 transcription levels. These data suggest that p38 MAPK plays an important role in the secretion of NO and IL-6 in LPS/IFN- gamma or TNF- alpha /IFN- gamma -treated MC3T3E-1 osteoblasts.

Antiangiogenic effect of KR31372 in rat sponge implant model

A rat sponge implant model was used to examine the antiangiogenic effect of KR31372. Topical administration of angiotensin II (AII, 100 ng, daily) into the sponges enhanced the basal sponge-induced neovascularization, leading to higher clearance of (99m)Tc, increased retention of dye in the vessels, and increased numbers of blood vessels. These AII-induced changes were significantly suppressed by oral administration of KR31372 (1 mg/kg for 7 days). Angiogenic effect of recombinant human VEGF(165) (200 ng) was modestly higher than that of AII, which was also significantly inhibited by KR31372. KR31372-mediated suppression of (99m)Tc clearance was reversed by glibenclamide. Levcromakalim showed a modestly suppressive effect on the AII-induced angiogenesis. In conclusion, KR31372 exerted a strong inhibitory effect on the sponge-induced neovascularization, in part, through mediation of glibenclamide-sensitive K(+) channel activation. It is suggested that it may have therapeutic potential in the treatment of angiogenic disorders.

Caspase-mediated cleavage of TRAF3 in FasL-stimulated Jurkat-T cells

The tumor necrosis factor receptor (TNFR)-associated factor (TRAF) proteins play a central role in the early steps of signal transduction by TNFR superfamily proteins, which induce various cellular responses, including apoptosis. Influences of TRAF proteins on the regulation of cell death and physical interactions between TRAFs and caspases have been reported. In this study, we demonstrate that TRAF3 is proteolyzed during cell death in a caspase-dependent manner. TRAF3 was found to be cleaved by incubation with caspase3 in vitro and by Fas- or CD3-triggering in Jurkat-T cells. The Fas- or CD3-induced cleavage of TRAF3 was blocked by caspase inhibitors and by introduction of alanine substitutions for D347 and D367 residues. Furthermore, the amino-terminal fragment of TRAF3 showed a different intracellular localization from the full-length TRAF3 with preferential distribution to particulate fractions and the nucleus. These findings suggest that TRAF3 may be regulated by caspases during apoptosis of T cells.

Proapoptotic effects of tau cleavage product generated by caspase-3

Using an in vitro translation assay to screen a human brain cDNA library, we isolated the microtubule-associated protein Tau and determined it to be a caspase-3 substrate whose C-terminal cleavage occurred during neuronal apoptosis. DeltaTau, the 50-kDa cleavage product, was detected by Western blot in apoptotic cortical cells probed with anti-PHF-1 and anti-Tau-5 antibodies, but not anti-T-46 antibody which recognizes the C-terminus. Overexpression of DeltaTau in SK-N-BE2(C) cells significantly increased the incidence of cell death. Staurosporine-induced Tau cleavage was blocked by 20 microM z-Asp-Glu-Val-Asp-chloromethylketone, a caspase-3 inhibitor, and in vitro, Tau was selectively cleaved by caspase-3 or calpain, a calcium-activated protease, but not by caspases-1, -8, or -9. (D421E)-Tau, a mutant in which Asp421 was replaced with a Glu, was resistant to cleavage by caspase-3 and tended to suppress staurosporine-induced cell death more efficiently than did wild-type Tau in both transient and stable expression systems. Finally, the incidence of DeltaTau-induced cell death was augmented by expression of Abeta precursor protein (APP) or Swedish APP mutant. Taken together, these results suggest that the caspase-3 cleavage product of Tau may contribute to the progression of neuronal cell death in Alzheimer's disease.

Preventing labyrinthitis ossificans: the role of steroids

OBJECTIVE

To identify a possible relationship between the administration of steroids at the time of diagnosis of bacterial meningitis and the development of labyrinthitis ossificans.

DESIGN

Retrospective analysis of the charts of 38 children requiring cochlear implantation who presented with bacterial meningitis and then developed bilateral profound deafness. The patients' charts were reviewed for age at diagnosis, the type of antibiotic administered, and the administration, dosage, and duration of steroid (dexamethasone) therapy. Labyrinthitis ossificans was established by preoperative computed tomographic and/or magnetic resonance imaging and by the intraoperative findings as described in the operative report.

PATIENTS AND METHODS

Patients were 38 children who received cochlear implantation by a single senior otolaryngologist for bacterial meningitis-related deafness. Ten patients' charts (26%) were available for full review; 9 of these 10 patients had documented pneumococcal meningitis and the other patient had Haemophilus influenzae-type meningitis.

RESULTS

One of the 6 patients who received steroid therapy at the time of initial illness had documented evidence of labyrinthitis ossificans either radiographically or at the time of surgery. All 4 patients who failed to receive steroid therapy developed labyrinthitis ossificans. The results achieve statistical significance by chi2 analysis and a t test (P<.01).

CONCLUSION

The results of this retrospective study are highly suggestive of a role for steroids in preventing the development of labyrinthitis ossificans in children with pneumococcal meningitis.

The p38 mitogen-activated protein kinase pathway regulates interleukin-6 synthesis in response to tumor necrosis factor in osteoblasts

The induction of interleukin-6 (IL-6), using a proinflammatory cytokine (tumor necrosis factor-alpha), was studied in a human osteoblast cell line (MG-63) in relation to p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappaB transcription factor. When added to MG-63 cells, tumor necrosis factor-alpha (TNF-alpha) had a stimulatory effect on the production of IL-6, and this elevation was significantly reduced by SB203580, a specific p38 MAPK inhibitor. In addition, the stimulation of IL-6 release was also reduced by pyrrolidine dithiocarbamate (PDTC) or NF-kappaB SN50, which has been reported to be a potent NF-kappaB inhibitor. Both the NF-kappaB inhibitors in the presence of SB203580 had a more inhibitory effect on IL-6 release. In this study, TNF-alpha stimulated NF-kappaB binding affinity as well as p38 MAP kinase activation, leading to the release of IL-6. However, the specific inhibitor of p38 MAPK, SB203580, had no effect on TNF-alpha-induced NF-kappaB activation and both NF-kappaB inhibitors failed to reduce the p38 MAPK activation in the TNF-alpha-stimulated osteoblasts. In addition, inhibition of p38 MAPK partially, but significantly, impaired TNF-alpha-regulated release of osteocalcin, an important differentiation marker in osteoblasts. These results strongly suggest that both p38 MAPK and NF-kappaB are required in TNF-alpha-induced IL-6 synthesis and that these two TNF-alpha-activated pathways can be primarily dissociated. Furthermore, p38 MAPK may play a significant role in differentiation in MG-63 cells.

N-butyl-2-cyanoacrylate pulmonary embolism after endoscopic injection sclerotherapy for gastric variceal bleeding

PURPOSE

The purpose of this work was to describe the radiologic and clinical manifestations of n-butyl-2-cyanoacrylate pulmonary embolism (PE) after endoscopic injection sclerotherapy (EIS) for gastric variceal bleeding.

METHOD

From 1992 to 1999, the medical records of 140 patients who had undergone EIS using n-butyl-2-cyanoacrylate were reviewed for identification of respiratory symptoms and amount of injection, and their pre- and postprocedure chest radiographs were reviewed to identify PE. In patients with PE, pre- and postprocedure chest radiographs (6/6), chest CT scans (3/6), lung perfusion scans (3/6), and follow-up chest radiographs (6/6) were analyzed retrospectively.

RESULTS

Radiographically evident PE was observed in 6 (4.3%) of 140 patients. In comparison with patients without emboli, these patients received a higher mean volume of injection (4.2 vs. 1.8 ml) (p = 0.0011). Four of the six patients with pulmonary emboli had respiratory symptoms. Chest radiographs and CT scans showed unusual tubular or nodular, radiopaque pulmonary emboli along the pulmonary vessels. Multiple peripheral, wedge-shaped, subsegmental perfusion defects were seen on perfusion lung scans. In five of six patients, the radiographic abnormalities showed complete or partial resolution. There were no fatalities directly associated with PE.

CONCLUSION

Radiographically evident PEs are uncommonly observed following EIS and appear to be more common in patients receiving a higher volume of liquid acrylate. Affected patients were either mildly symptomatic or asymptomatic, and there were no direct fatalities of this complication.

Activation of c-Jun N-terminal kinase and activator protein 1 by receptor activator of nuclear factor kappaB

Receptor activator of nuclear factor kappaB (RANK), a lately identified member of the tumor necrosis factor receptor superfamily, plays important roles both in osteoclastogenesis and in lymph node development. Previously, we and others showed that RANK could stimulate the activity of c-Jun N-terminal kinase (JNK). In this study, we investigated the mechanism by which RANK activates JNK. We found that N-terminal deletion mutants of tumor necrosis factor receptor-associated factor 2 and 6 were inhibitory to RANK activation of JNK. The JNK activation by RANK was also reduced by cotransfection of kinase-inactive mutants of apoptosis signal-regulating kinase 1, MAPK/ERK kinase kinase 1, and nuclear factor kappaB-inducing kinase. In addition, dominant negative mutants of Rac and Ras decreased the RANK stimulation of JNK activity. Furthermore, we determined whether the RANK engagement of JNK signaling pathways could lead to the activation of the activator protein 1 (AP-1) transcription factor, one of the potential downstream targets of activated JNK. RANK was found to activate AP-1 in a manner dependent on the signaling molecules involved in the JNK activation by this receptor. Furthermore, the activation of JNK and ERK, but not that of p38, appeared to be involved in the AP-1 activation by RANK. Thus, RANK may use both JNK and ERK pathways to signal to the AP-1 transcription factor.

Kaposi's sarcoma involving a transplanted kidney, ureter and urinary bladder: ultrasound and CT findings

We report the imaging findings in a case of Kaposi's sarcoma involving a transplanted kidney, ureter and urinary bladder. Ultrasound and CT demonstrated multiple nodular masses in the pelvis of the transplanted kidney, ureter and bladder. The masses enhanced well on CT following i.v. contrast medium.

KR 31372, a benzopyran derivative, inhibits oxidized LDL-stimulated proliferation and migration of vascular smooth muscle cells

KR 31372 is a benzopyran derivative. Both [3H]thymidine incorporation and migrations (chemotactic and wound-edge) of cultured smooth muscle cells (SMCs) were greatly stimulated by oxidized low-density lipoprotein (LDL). These effects were significantly suppressed by KR 31372 (10(7) - 10(6) M) and PDGF-BB antibody (10(8) - 10(6) M). Preincubation with KR 31372 led to a decrease in the synthesis of PDGF-BB-like immunoreactivity (PDGF-BB-LI) that had been stimulated by oxidized LDL. Otherwise, KR 31372 and probucol strongly inhibited the production of thiobarbituric acid reactive substances (TBARS) caused by the incubation of LDL with Cu2+ ion, and significantly reduced the intracellular oxidative stress when stimulated with H,O2. Taken together, it is suggested that KR 31372 may inhibit the oxidized LDL-stimulated syntheses of DNA and PDGF-BB, and migration of the SMCs, in part, via the antioxidant activity.

Mediastinal lymphadenopathy in pulmonary fibrosis: correlation with disease severity

OBJECTIVE

To evaluate the relationship between mediastinal lymph node enlargement and disease severity score in patients with pulmonary fibrosis.

MATERIALS AND METHODS

A retrospective study included 30 patients with pulmonary fibrosis: idiopathic pulmonary fibrosis (n = 25), usual interstitial pneumonia (UIP) associated with collagen vascular disease (n = 4), and UIP associated with hepatitis C (n = 1). Disease severity was determined by a computed tomography (CT) scoring system. Each patient's lobe was scored by two radiologists on a scale of 0-5 for both ground glass opacity (GGO) and fibrosis. The presence, number, and sites of enlarged nodes (short axis > or = 10 mm) were assessed. CT severity scores were compared with total number of enlarged lymph nodes (L/Ns) and short axis diameter of the largest L/N (LLN). According to each severity score, patients were divided into two groups: the GGO-predominant group (n = 10) and the fibrosis-predominant group (n = 20). Total numbers of enlarged L/Ns and short axis diameter of LLN were compared in each group.

RESULTS

Enlarged mediastinal L/Ns were present in 86%. Total severity score, GGO score, and fibrosis score strongly correlated with total number of enlarged L/Ns (p<0.05). Total severity score and GGO score correlated well with short axis diameter of LLN; however, the fibrosis score did not correlate with the short axis diameter of LLN. In respect to total number of enlarged L/Ns, the difference between the GGO group and fibrosis group was not apparent. In respect to the short axis diameter of LLN, the GGO group LLN was larger in diameter than the fibrosis group LLN (p<0.05).

CONCLUSION

The greater the severity score of pulmonary fibrosis, the larger the total number of enlarged L/Ns. Those patients with more GGO had larger lymph nodes.

The value of CT-guided percutaneous needle aspiration in immunocompromised patients with suspected pulmonary infection

OBJECTIVE

We evaluated the diagnostic efficacy of CT-guided percutaneous needle aspiration in immunocompromised patients with suspected pulmonary infection.

SUBJECTS AND METHODS

We reviewed the findings and yields of 24 CT-guided percutaneous needle aspirations in 21 immunocompromised patients. Cytologic evaluation and culture for aerobes, anaerobes, Mycobacterium species, and fungus were performed in all aspirates.

RESULTS

We identified one or more etiologic microorganisms in 19 (79.2%) of 24 CT-guided percutaneous needle aspirations. Of 19 aspirates with positive findings, single causal microorganisms were identified in 18. Staphylococcus aureus was found in four aspirates, and Aspergillus fumigatus in seven; these microorganisms were the principal bacterial (4/11) and fungal (7/9) causative organisms. One of the 19 aspirates with positive findings yielded two microorganisms. In the remaining five aspirates, no microorganisms were identified and cytologic examination revealed nonspecific inflammatory cells. No major complications were observed during or after the procedure.

CONCLUSION

CT-guided percutaneous needle aspiration is a safe and useful diagnostic method for the identification of specific microorganisms in immunocompromised patients with suspected pulmonary infection.

Activation of c-jun N-terminal kinase by 4-1BB (CD137), a T cell co-stimulatory molecule

It has been widely accepted that T cell activation requires two signals; one from the binding of the antigen/major histocompatibility complex to the T-cell receptor (TCR)/CD3 complex and the other from the interaction between a surface molecule on antigen presenting cells and its receptor on T cells. The second signal is considered as co-stimulatory and the B7/CD28 pair has been well studied as a prototype. Recently 4-1BB (CD137) has been characterized as another co-stimulatory molecule for T cell activation. However, unlike the CD28/B7 pair, 4-1BB and its ligand 4-1BBL constitute a member of the tumor necrosis factor (TNF) receptor/TNF pair superfamily. The signaling mechanism of 4-1BB has not been revealed in detail. To investigate whether 4-1BB takes the signaling pathways analogous to those for TNF receptors, we generated polyclonal antibodies against human 4-1BB and 4-1BBL and established stable transfectants of the receptor and the ligand with a high level of cell surface expression. Over-expression of h4-1BB was found to result in the activation of c-Jun N-terminal kinase (JNK) in the human embryonic kidney cell line 293. In T cells, it has been previously demonstrated that JNK activation requires dual signals such as the ligation of TCR/CD3 complex plus CD28 co-stimulation or PMA plus ionomycin. The JNK activation by 4-1BB in Jurkat T cells was also found to require stimulation of the TCR/CD3 complex, consistent with the notion that 4-1BB functions as a co-stimulatory molecule for T cell activation.

Laparoscopic nephrectomy for nonfunctioning tuberculous kidney

BACKGROUND AND PURPOSE

Although laparoscopic nephrectomy for benign renal disease has been widely accepted, use of the operation for tubercular pyelonephritic kidney is relatively contraindicated because of difficulties in dissecting the dense fibrotic adhesions and the risk of spillage of caseous materials with subsequent dissemination of the disease. However, with the accumulation of experience, laparoscopic surgery is expanding its applications. In this study, we tried to evaluate the efficacy and safety of the laparoscopic nephrectomy for renal tuberculosis.

PATIENTS AND METHODS

At three centers, 13 laparoscopic nephrectomies were performed between April 1996 and March 1999. The patients consisted of eight men and five women with a mean age of 44.8 years (range 37-51 years). All patients had known renal tuberculosis with a nonfunctioning kidney and underwent nephrectomy after at least 3 months of chemotherapy with four antituberculous drugs. Nine patients underwent the transperitoneal approach and four patients, the retroperitoneal approach. The follow-up was from 2 to 35 months with a mean of 15.8 months.

RESULTS

Kidneys were removed laparoscopically in 12 patients (92%). The mean operative time was 268 minutes (range 190-500 minutes), and the mean estimated blood loss was 227 mL. Although there had been some difficulties releasing the adhesions, no significant intraoperative and postoperative complications were observed. Conversion to open surgery was needed in only one patient. The mean hospital stay was 4 days, and the patients returned to normal activity within 10 days. Neither local recurrence nor distant dissemination of the disease was observed during the follow-up period.

CONCLUSION

Laparoscopic nephrectomy for renal tuberculosis was safe and effective with minor complications. Therefore, tuberculosis should not be a contraindication to a laparoscopic approach.

Hepatic expression, synthesis and secretion of a novel fibrinogen/angiopoietin-related protein that prevents endothelial-cell apoptosis

Using degenerate PCR we isolated a cDNA encoding a novel 406- and 410-amino acid protein from human and mouse embryonic cDNAs and have designated it 'hepatic fibrinogen/angiopoietin-related protein' (HFARP). The N-terminal and C-terminal portions of HFARP contain the characteristic coiled-coil domains and fibrinogen-like domains that are conserved in angiopoietins. In human and mouse tissues, HFARP mRNA is specifically expressed in the liver. HFARP mRNA and protein are mainly present in the hepatocytes. HFARP has a highly hydrophobic region at the N-terminus that is typical of a secretory signal sequence and one consensus glycosylation site. Recombinant HFARP expressed in COS-7 cells is secreted and glycosylated. HFARP protein is present not only in the hepatocytes, but also in the circulating blood. Recombinant HFARP acts as an apoptosis survival factor for vascular endothelial cells, but does not bind to Tie1 or Tie2 (endothelial-cell tyrosine kinase receptors). These results suggest that HFARP may exert a protective function on endothelial cells through an endocrine action.

Diarylheptanoids from the leaves of Alnus hirsuta Turcz

Diarylheptanoids, (5S)-1,7-bis-(3,4-dihydroxyphenyl)-5-hydroxyheptane-3-one (1, hirsutanonol), (5S)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-3-one-5-O-beta-D-xylopyranosi de (2, oregonin), (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-beta-D-xylopyranoside (3), and (5R)-1,7-bis-(3,4-dihydroxyphenyl)-heptane-5-O-beta-D-glucopyranoside (4) were isolated from the leaves of Alnus hirsuta Turcz. The structures of these compounds were identified based on the spectral and physicochemical data.

Anticancer activity of hydrophobic peptides from soy proteins

An anticancer peptide from soy protein was purified and isolated. Defatted soy protein was hydrolyzed with thermoase and hydrophobic peptides were extracted with ethanol. The peptide extract was fractionated by XAD-2 hydrophobic, gel filtration chromatography, and different C18 HPLCs. Anticancer activity of each fraction was assayed by measuring in vitro cytotoxicity on P388D1, a mouse monocyte macrophage cell line. IC50 value of a peptide fraction from Sephadex G-25 chromatography was 0.16 mg/ml. This peptide fraction at 1 mg/ml significantly affected cell cycle progression by arresting P388D1 at G2/M phases. Finally purified peptide from analytical C18 HPLC was nonapeptide of which molecular weight was 1157 Da and the sequence was X-Met-Leu-Pro-Ser-Tye-Ser-Pro-Tyr.

Electrochemical studies of a truncated laccase produced in Pichia pastoris

The cDNA that encodes an isoform of laccase from Trametes versicolor (LCCI), as well as a truncated version (LCCIa), was subcloned and expressed by using the yeast Pichia pastoris as the heterologous host. The amino acid sequence of LCCIa is identical to that of LCCI except that the final 11 amino acids at the C terminus of LCCI are replaced with a single cysteine residue. This modification was introduced for the purpose of improving the kinetics of electron transfer between an electrode and the copper-containing active site of laccase. The two laccases (LCCI and LCCIa) are compared in terms of their relative activity with two substrates that have different redox potentials. Results from electrochemical studies on solutions containing LCCI and LCCIa indicate that the redox potential of the active site of LCCIa is shifted to more negative values (411 mV versus normal hydrogen electrode voltage) than that found in other fungal laccases. In addition, replacing the 11 codons at the C terminus of the laccase gene with a single cysteine codon (i.e., LCCI-->LCCIa) influences the rate of heterogeneous electron transfer between an electrode and the copper-containing active site (k(het) for LCCIa = 1.3 x 10(-4) cm s(-1)). These results demonstrate for the first time that the rate of electron transfer between an oxidoreductase and an electrode can be enhanced by changes to the primary structure of a protein via site-directed mutagenesis.

SKP-450 inhibits migration and DNA synthesis stimulated by oxidized low density lipoprotein in smooth muscle cells

This study was carried out to examine the inhibitory effects of SKP-450 (2-[2"(1", 3"-dioxolone)-2-methyl]-4-(2'-oxo-1'-pyrrolidinyl)-6-nitro-2H-1-be nzo pyran), a potassium channel opener, on the proliferation and migration stimulated by oxidized low density lipoprotein (LDL) of cultured smooth muscle cells of Wistar Kyoto rat aorta. SKP-450 (10(-7) and 10(-6) M) as well as probucol (10(-7)-10(-5) M) reduced the production of thiobarbituric acid reactive substances from LDL submitted to CuSO(4) (10 microM). The increased [3H]thymidine incorporation and migration (chemotactic and wound-edge) of the cultured smooth muscle cells in association with increased production of platelet-derived growth factor (PDGF)-BB-like immunoreactivity stimulated by oxidized LDL were significantly reduced by SKP-450 (10(-7)-10(-6) M). Inhibition by SKP-450 of the oxidized LDL-stimulated [3H]thymidine incorporation was antagonized by iberiotoxin (10(-7) M), but not by glibenclamide (10(-6) M), suggestive of mediation of Ca(2+)-activated K(+) channel opening in the action of SKP-450. Taken together, SKP-450 inhibited the proliferation and migration of the smooth muscle cells as well as PDGF production stimulated by oxidized LDL, accompanying with its antiperoxidative action.

A prospective transesophageal echocardiographic study to assess a new type of left atrial spontaneous contrast at rest and during respiratory manoeuvres

BACKGROUND

Recent observations suggest that a spontaneous echocardiographic contrast with fast motion (FEC) mimicking intravenous contrast can be seen in the left atrium in the absence of intravenous contrast injection.

OBJECTIVE

To assess the incidence of FEC and to evaluate the differentiating features between FEC and injected saline contrast.

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary referral centre.

PATIENTS AND METHODS

Transesophageal echocardiography was performed in 91 consecutive patients with a mean age of 58+/-15 years. Patients with mechanical valves and congenital heart disease were excluded. Images of the right atrium, left atrium and pulmonary veins were obtained in the absence of an intravenous catheter during quiet respiration, cough and the Valsalva manoeuvre. The same procedure was repeated during injection with agitated saline after venous cannulation.

RESULTS

In the absence of intravenous cannulation, FEC was detected in eight patients (9%) during quiet respiration, 36 patients (40%) during cough and 55 patients (60%) during the Valsalva manoeuvre. During the Valsalva manoeuvre, FEC was detected in the right atrium in 41 patients (45%) and in the left atrium in 33 patients (36%) (P=0.15). FEC was not related to a history of embolic event, left atrial smoke or patent foramen ovale. Intra- and interobserver agreements in the detection of FEC were 96% and 90%, respectively.

CONCLUSIONS

FEC can be observed frequently in the left atrium during cough or the Valsalva manoeuvre, and awareness of FEC is important to avoid the erroneous diagnosis of patent foramen ovale.