In vivo evidence that erythropoietin protects neurons from ischemic damage

Erythropoietin (EPO) produced by the kidney and the liver (in fetuses) stimulates erythropoiesis. In the central nervous system, neurons express EPO receptor (EPOR) and astrocytes produce EPO. EPO has been shown to protect primary cultured neurons from N-methyl-D-aspartate (NMDA) receptor-mediated glutamate toxicity. Here we report in vivo evidence that EPO protects neurons against ischemia-induced cell death. Infusion of EPO into the lateral ventricles of gerbils prevented ischemia-induced learning disability and rescued hippocampal CA1 neurons from lethal ischemic damage. The neuroprotective action of exogenous EPO was also confirmed by counting synapses in the hippocampal CA1 region. Infusion of soluble EPOR (an extracellular domain capable of binding with the ligand) into animals given a mild ischemic treatment that did not produce neuronal damage, caused neuronal degeneration and impaired learning ability, whereas infusion of the heat-denatured soluble EPOR was not detrimental, demonstrating that the endogenous brain EPO is crucial for neuronal survival. The presence of EPO in neuron cultures did not repress a NMDA receptor-mediated increase in intracellular Ca2+, but rescued the neurons from NO-induced death. Taken together EPO may exert its neuroprotective effect by reducing the NO-mediated formation of free radicals or antagonizing their toxicity.

Mechanisms of action of cyclosporine

Cyclosporine (cyclosporin A, CsA) has potent immunosuppressive properties, reflecting its ability to block the transcription of cytokine genes in activated T cells. It is well established that CsA through formation of a complex with cyclophilin inhibits the phosphatase activity of calcineurin, which regulates nuclear translocation and subsequent activation of NFAT transcription factors. In addition to the calcineurin/NFAT pathway, recent studies indicate that CsA also blocks the activation of JNK and p38 signaling pathways triggered by antigen recognition, making CsA a highly specific inhibitor of T cell activation. Here we discuss the action of CsA on JNK and p38 activation pathways. We also argue the potential of CsA and its natural counterparts as pharmacological probes.

In vitro effects on microtubule dynamics of purified Xenopus M phase-activated MAP kinase

The protein kinase MAP kinase, also called MAP2 kinase, is a serine/threonine kinase whose activation and phosphorylation are induced by a variety of mitogens, and which is thought to have a critical role in a network of protein kinases in mitogenic signal transduction. A burst in kinase activation and protein phosphorylation may also be important in triggering the dramatic reorganization of the cell during the transition from interphase to mitosis. The interphase-metaphase transition of microtubule arrays is under the control of p34cdc2 kinase, a central control element in the G2-M transition of the cell cycle. Here we show that a Xenopus kinase, closely related to the mitogen-activated mammalian MAP kinase, is phosphorylated and activated during M phase of meiotic and mitotic cell cycles, and that the interphase-metaphase transition of microtubule arrays can be induced by the addition of purified Xenopus M phase-activated MAP kinase or mammalian mitogen-activated MAP kinase to interphase extracts in vitro.

TAK1 mediates the ceramide signaling to stress-activated protein kinase/c-Jun N-terminal kinase

Ceramide has been proposed as a second messenger molecule implicated in a variety of biological processes. It has recently been reported that ceramide activates stress-activated protein kinase (SAPK, also known as c-Jun NH2-terminal kinase JNK), a subfamily member of mitogen-activated protein kinase superfamily molecules and that the ceramide/SAPK/JNK signaling pathway is required for stress-induced apoptosis. However, the molecular mechanism by which ceramide induces SAPK/JNK activation is unknown. Here we show that TAK1, a member of the mitogen-activated protein kinase kinase kinase family, is activated by treatment of cells with agents and stresses that induce an increase in ceramide. Ceramide itself stimulated the kinase activity of TAK1. Expression of a constitutively active form of TAK1 resulted in activation of SAPK/JNK and SEK1/MKK4, a direct activator of SAPK/JNK. Furthermore, expression of a kinase-negative form of TAK1 interfered with the activation of SAPK/JNK induced by ceramide. These results indicate that TAK1 may function as a mediator of ceramide signaling to SAPK/JNK activation.

Microglia-derived interleukin-6 and leukaemia inhibitory factor promote astrocytic differentiation of neural stem/progenitor cells

Neural stem/progenitor cells (NSPCs) proliferate and differentiate depending on their intrinsic properties and local environment. It has been recognized that astrocytes promote neurogenic differentiation of NSPCs, suggesting the importance of cell-cell interactions between glial cells and NSPCs. Recent studies have demonstrated that microglia, one type of glial cells, play an important role in neurogenesis. However, little is known about how activated microglia control the proliferation and differentiation of NSPCs. In this study, we investigated the possibility that microglia-derived soluble factors regulate the behaviour of NSPCs. To this end, NSPCs and microglial cultures were obtained from rat embryonic day 16 subventricular zone (SVZ) and rat postnatal 1 day cortex, respectively, and the conditioned medium from microglia was prepared. Microglial-conditioned medium had no significant effect on the proliferation of NSPCs. In contrast, it increased the percentage of cells positive for a marker of astrocytes, glial fibrillary acidic protein (GFAP) during differentiation. The induction of astrocytic differentiation by microglial-conditioned medium was reduced by the inhibition of the Janus kinase/signal transducer and activation of transcription (JAK/STAT) and mitogen-activated protein kinase (MAPK) pathways. Furthermore, microglia-derived interleukin (IL)-6 and leukaemia inhibitory factor (LIF) were identified as essential molecules for this astrocytic differentiation using neutralizing antibodies and recombinant cytokines. Our results suggest that microglia as well as astrocytes contribute to the integrity of the local environment of NSPCs, and at least IL-6 and LIF released by activated microglia promote astrocytic differentiation of NSPCs via the activation of the JAK/STAT and MAPK pathways.

Bone lengthening in rabbits by callus distraction. The role of periosteum and endosteum

The histology and mechanics of leg lengthening by callus distraction were studied in 27 growing rabbits. Tibial diaphyses were subjected to subperiosteal osteotomy, held in a neutral position for 10 days and then slowly distracted at 0.25 mm/12 hours, using a dynamic external fixator. Radiographs showed that the gap became filled with callus having three distinct zones. Elongation appeared to occur in a central radiolucent zone; this was bounded by two sclerotic zones. Histologically, the radiolucent zone consisted of longitudinally arranged cartilage and fibrous tissue while the sclerotic zones were formed by fine cancellous bone. New bone occasionally contained islands of cartilage, suggesting it had been formed by endochondral ossification. After completion of distraction, the two sclerotic zones fused, shrank and were eventually absorbed, leaving tubular bone with a new cortex. When the periosteum had been removed at the operation, callus formation was markedly disturbed and there was failure of bone lengthening. Scraping of endosteum, in contrast, did not have a pronounced effect. These results suggest that the preservation of periosteum is essential if bone lengthening by callus distraction is to succeed, and that preservation of the periosteum is more important than careful corticotomy.

Rad52 forms ring structures and co-operates with RPA in single-strand DNA annealing

BACKGROUND

The RAD52 epistasis group in Saccharomyces cerevisiae is involved in various types of homologous recombination including recombinational double-strand break (DSB) repair and meiotic recombination. A RecA homologue, Rad51, plays a pivotal role in homology search and strand exchange. Genetic analysis has shown that among members of its epistasis group, RAD52 alone is required for recombination between direct repeats yielding deletions. Very little has been discovered about the biochemical roles and structure of the Rad52 protein.

RESULTS

Purified Rad52 protein binds to both single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). Electron microscope observations revealed that Rad52 molecules form multimeric rings. An increase in the intensity of fluorescence when Rad52 is bound to epsilonDNA showed an alteration of the structure of ssDNA. RPA was binding to Rad52 and enhanced the annealing of complementary ssDNA molecules. This enhancement was not observed in Escherichia coli SSB protein or T4 phage gp32 protein.

CONCLUSION

Rad52 forms a ring-like structure and binds to ssDNA. Its structure and DNA binding properties are different from those of Rad51. The interaction of Rad52 with RPA plays an important role in the enhancement of annealing of complementary ssDNAs. We therefore propose that Rad52 mediates the RAD51-independent recombination through an ssDNA annealing, assisted by RPA.

Disruption of AMPA receptor GluR2 clusters following long-term depression induction in cerebellar Purkinje neurons

Cerebellar long-term depression (LTD) is thought to play an important role in certain types of motor learning. However, the molecular mechanisms underlying this event have not been clarified. Here, using cultured Purkinje cells, we show that stimulations inducing cerebellar LTD cause phosphorylation of Ser880 in the intracellular C-terminal domain of the AMPA receptor subunit GluR2. This phosphorylation is accompanied by both a reduction in the affinity of GluR2 to glutamate receptor interacting protein (GRIP), a molecule known to be critical for AMPA receptor clustering, and a significant disruption of postsynaptic GluR2 clusters. Moreover, GluR2 protein released from GRIP is shown to be internalized. These results suggest that the dissociation of postsynaptic GluR2 clusters and subsequent internalization of the receptor protein, initiated by the phosphorylation of Ser880, are the mechanisms underlying the induction of cerebellar LTD.

ERK and p38 MAPK, but not NF-kappaB, are critically involved in reactive oxygen species-mediated induction of IL-6 by angiotensin II in cardiac fibroblasts

We recently reported that angiotensin II (Ang II) induced IL-6 mRNA expression in cardiac fibroblasts, which played an important role in Ang II-induced cardiac hypertrophy in paracrine fashion. The present study investigated the regulatory mechanism of Ang II-induced IL-6 gene expression, focusing especially on reactive oxygen species (ROS)-mediated signaling in cardiac fibroblasts. Ang II increased intracellular ROS in cardiac fibroblasts, and the increase was completely inhibited by the AT-1 blocker candesartan and the NADH/NADPH oxidase inhibitor diphenyleneiodonium (DPI). We first confirmed that antioxidant N-acetylcysteine, superoxide scavenger Tiron, and DPI suppressed Ang II-induced IL-6 expression. Because we observed that exogenous H(2)O(2) also increased IL-6 mRNA, the signaling pathways downstream of Ang II and exogenous H(2)O(2) were compared. Ang II, as well as exogenous H(2)O(2), activated ERK, p38 MAPK, and JNK, which were significantly inhibited by N-acetylcysteine and DPI. In contrast with exogenous H(2)O(2), however, Ang II did not influence phosphorylation and degradation of IkappaB-alpha/beta or nuclear translocation of p65, nor did it increase NF-kappaB promoter activity. PD98059 and SB203580 inhibited Ang II-induced IL-6 expression. Truncation and mutational analysis of the IL-6 gene promoter showed that CRE was an important cis-element in Ang II-induced IL-6 gene expression. NF-kappaB-binding site was important for the basal expression of IL-6, but was not activated by Ang II. Ang II phosphorylated CREB through the ERK and p38 MAPK pathway in a ROS-sensitive manner. Collectively, these data indicated that Ang II stimulated ROS production via the AT1 receptor and NADH/NADPH oxidase, and that these ROS mediated activation of MAPKs, which culminated in IL-6 gene expression through a CRE-dependent, but not NF-kappaB-dependent, pathway in cardiac fibroblasts.

Phosphorylation of serine-880 in GluR2 by protein kinase C prevents its C terminus from binding with glutamate receptor-interacting protein

Phosphorylation of the glutamate receptor is an important mechanism of synaptic plasticity. Here, we show that the C terminus of GluR2 of the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptor is phosphorylated by protein kinase C and that serine-880 is the major phosphorylation site. This phosphorylation also occurs in human embryonic kidney (HEK) cells by addition of 12-O-tetradecanoylphorbol 13-acetate. Our immunoprecipitation experiment revealed that the phosphorylation of serine-880 in GluR2 drastically reduced the affinity for glutamate receptor-interacting protein (GRIP), a synaptic PDZ domain-containing protein, in vitro and in HEK cells. This result suggests that modulation of serine-880 phosphorylation in GluR2 controls the clustering of AMPA receptors at excitatory synapses and consequently contributes to synaptic plasticity.

In search of a function for the TIS21/PC3/BTG1/TOB family

The Btg family of anti-proliferative gene products includes Pc 3/Tis 21/Btg 2, Btg 1, Tob, Tob2, Ana/Btg3, Pc3k and others. These proteins are characterized by similarities in their amino-terminal region: the Btg1 homology domain. However, the pleiotropic nature of these family proteins has been observed and no common physiological function among family members was suggested from the history of their identification. Recent progress in the search for Btg family functions has come from the analysis of cell regulation and of cell differentiation. It is now emerging that every member of this family has a potential to regulate cell growth. We would like to propose here to use a nomenclature APRO as a new term for the family.

The gene encoding a newly discovered protein, chorein, is mutated in chorea-acanthocytosis

Chorea-acanthocytosis is a neurodegenerative disorder with peripheral red cell acanthocytosis. Linkage of chorea-acanthocytosis to chromosome 9q21 has been found. We refined the locus region and identified a previously unknown, full-length cDNA encoding a presumably structural protein, which we called chorein. We found a deletion in the coding region of the cDNA leading to a frame shift resulting in the production of a truncated protein in both alleles of patients and in single alleles of obligate carriers.

Radical operations for carcinoma of the gallbladder: present status in Japan

Based on the histological findings of 1,686 resected cases of gallbladder carcinoma and operative results collected from 172 major hospitals in Japan, the present status of radical operation was assessed with respect to the relationship between the depth of carcinoma invasion and the operative results. The depth of carcinoma invasion was classified into 5 groups, i.e., limited to the mucosal layer (m) in 11.9%, advanced to the proper muscle layer (pm) in 9.8%, extending to the subserosal layer (ss) in 29.6%, serosal involvement (se) in 21.8%, and carcinoma invading the adjacent organs (si) in 26.9%. Tumor extension, such as lymph node metastasis, invasion of lymphatic and venous vessels, and perineural infiltration, were observed more frequently in patients with ss, se, and si than in those with m and pm. The cumulative 5-year survival rates were 82.6% and 72.5% in patients with m and pm, which were significantly higher than 37.0%, 14.7%, and 7.5% in those with ss, se, and si, respectively. The choice of operative procedures should depend on the depth of carcinoma invasion. Cholecystectomy alone is done only in patients with tumor limited to the mucosa, and more radical procedures such as extended cholecystectomy should be performed in those with carcinoma invasion beyond the mucosa. Pancreatoduodenectomy is indicated in those with lymph node metastasis posterior to the head of the pancreas and with invasion to the duodenum. When the tumor directly invades the liver, major hepatic resection is recommended.(ABSTRACT TRUNCATED AT 250 WORDS)

The Impact of Postoperative Complications on Survivals After Esophagectomy for Esophageal Cancer

The aim of this study was to assess the impact of postoperative complications after esophagectomy on long-term outcome.The treatment of esophageal cancer has recently been improved; however, esophagectomy with thoracotomy and laparotomy carries considerable postoperative morbidity and mortality. The real impact of postoperative complications on overall survival is still under evaluation.A retrospective analysis was performed on patients with esophageal cancer who underwent esophagectomy with thoracotomy and laparotomy, with R0 or R1 resection between January 1997 and December 2012. Of 402 patients, we analyzed the following parameters 284 patients who could be followed up for over 5 years: stage of disease, neoadjuvant therapies, surgical approaches, surgical complications, postoperative medical complications, and overall and relapse-free survivals using medical records.Of the 284 patients, 64 (22.5%) had pneumonia, 55 (19.4%) had anastomotic leakage, and 45 (15.8%) had recurrent laryngeal nerve paralysis (RLNP). Pneumonia had a significant negative impact on overall survival (P = 0.035); however, anastomotic leakage and RLNP did not affect overall survival. Multivariate analysis revealed that the presence of pneumonia was predictive of poorer overall survival; the multivariate hazard ratio was 1.456 (95% confidence interval 1.020-2.079, P = 0.039).Pneumonia has a negative impact on overall survival after esophagectomy. Strategies to prevent pneumonia after esophagectomy should improve outcomes in this operation.

Synergistic effects of IL-4 and IL-18 on IL-12-dependent IFN-gamma production by dendritic cells

Mouse splenic dendritic cells (DCs) produce IFN-gamma in response to IL-12. In the present study, we analyzed effects of Th1 and Th2 cytokines on IFN-gamma production by DCs. IL-18 produced by DCs and macrophages acts in an autocrine manner and augments IL-12-induced IFN-gamma production by DCs as also observed in T and NK cells. Surprisingly, IL-4, a Th2 cytokine, also acts synergistically with IL-12 on IFN-gamma production by DCs. In addition, IL-4 markedly enhances IFN-gamma production when DCs are stimulated through CD40 or MHC class II. These results indicate that both Th1 and Th2 cytokines act on DCs during T cell-DC interaction upon Ag presentation. p38 mitogen-activated protein kinase is constitutively activated in mature DCs and is required for IFN-gamma production by DCs. IL-18 but not IL-4 or IL-12 further activates the p38 mitogen-activated protein kinase activity, suggesting that IL-4 and IL-18 enhance IFN-gamma production through distinct intracellular signal transduction pathways in DCs.

Xenopus MAP kinase activator: identification and function as a key intermediate in the phosphorylation cascade

MAP kinase is thought to play a pivotal role not only in the growth factor-stimulated signalling pathway but also in the M phase phosphorylation cascade downstream of MPF. MAP kinase is fully active only when both tyrosine and threonine/serine residues are phosphorylated. We have now identified and purified a Xenopus MAP kinase activator from mature oocytes that is able to induce activation and phosphorylation on tyrosine and threonine/serine residues of an inactive form of Xenopus MAP kinase. The Xenopus MAP kinase activator itself is a 45 kDa phosphoprotein and is inactivated by protein phosphatase 2A treatment in vitro. Microinjection of the purified activator into immature oocytes results in immediate activation of MAP kinase. Further experiments using microinjection as well as cell free extracts have shown that Xenopus MAP kinase activator is an intermediate between MPF and MAP kinase. Thus, MAP kinase activator plays a key role in the phosphorylation cascade.

Xenopus M phase MAP kinase: isolation of its cDNA and activation by MPF

MAP kinase is activated and phosphorylated during M phase of the Xenopus oocyte cell cycle, and induces the interphase-M phase transition of microtubule dynamics in vitro. We have carried out molecular cloning of Xenopus M phase MAP kinase and report its entire amino acid sequence. There is no marked change in the MAP kinase mRNA level during the cell cycle. Moreover, studies with an anti-MAP kinase antiserum indicate that MAP kinase activity may be regulated posttranslationally, most likely by phosphorylation. We show that MAP kinase can be activated by microinjection of MPF into immature oocytes or by adding MPF to cell-free extracts of interphase eggs. These results suggest that MAP kinase functions as an intermediate between MPF and the interphase-M phase transition of microtubule organization.

Dietary supplementation with fish oil rich in omega-3 polyunsaturated fatty acids in children with bronchial asthma

Omega-3 polyunsaturated fatty acids have anti-inflammatory effects in vitro, and high dietary levels are associated with a lower incidence of inflammatory diseases. However, only limited effects have been demonstrated in asthma. The effects of dietary supplementation with fish oil for 10 months in 29 children with bronchial asthma was investigated in a randomized controlled fashion. In order to minimize the effects of environmental inhaled allergens and diet, this study was performed in a long-term treatment hospital. Subjects received fish oil capsules containing 84 mg eicosapentaenoic acid (EPA) and 36 mg docosahexaenoic acid (DHA) or control capsules containing 300 mg olive oil. The daily dosages of EPA and DHA were 17.0-26.8 and 7.3-11.5 mg x kg body weight(-1), respectively. Asthma symptom scores decreased and responsiveness to acetylcholine decreased in the fish oil group but not in the control group. In addition, plasma EPA levels increased significantly only in the fish oil group (p<0.0088). No significant side-effects were observed. The present results suggest that dietary supplementation with fish oil rich in the omega-3 polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid is beneficial for children with bronchial asthma in a strictly controlled environment in terms of inhalant allergens and diet.

Dietary regulation of PI3K/AKT/GSK-3β pathway in Alzheimer's disease

Alzheimer’s disease (AD) is characterized by the formation of senile plaques and neurofibrillary tangles composed of phosphorylated Tau. Several findings suggest that correcting signal dysregulation for Tau phosphorylation in AD may offer a potential therapeutic approach. The PI3K/AKT/GSK-3β pathway has been shown to play a pivotal role in neuroprotection, enhancing cell survival by stimulating cell proliferation and inhibiting apoptosis. This pathway appears to be crucial in AD because it promotes protein hyper-phosphorylation in Tau. Understanding those regulations may provide a better efficacy of new therapeutic approaches. In this review, we summarize advances in the involvement of the PI3K/AKT/GSK-3β pathways in cell signaling of neuronal cells. We also review recent studies on the features of several diets and the signaling pathway involved in AD.

T lymphocyte activation signals for interleukin-2 production involve activation of MKK6-p38 and MKK7-SAPK/JNK signaling pathways sensitive to cyclosporin A

p38/CSBP, a subgroup member of mitogen-activated protein kinase (MAPK) superfamily molecules, is known to be activated by proinflammatory cytokines and environmental stresses. We report here that p38 is specifically activated by signals that lead to interleukin-2 (IL-2) production in T lymphocytes. A p38 activator MKK6 was also markedly activated by the same stimulation. Pretreatment of cells with SB203580, a specific inhibitor of p38, as well as expression of a dominant-negative mutant of MKK6, suppressed the transcriptional activation of the IL-2 promoter. We also demonstrated that MKK7, a recently described MAPK kinase family member, plays a major role in the activation of stress-activated protein kinase (SAPK)/c-Jun NH2-terminal kinase (JNK) in T lymphocytes. Moreover, a dominant-negative mutant of MKK7 abrogated the transcriptional activation of the distal nuclear factor of activated T cells response element in the IL-2 promoter. Cyclosporin A, a potent immunosuppressant, inhibited activation of both p38 and SAPK/JNK pathways but not the MAPK/extracellular signal-regulated kinase (ERK) pathway. Our results indicate that both MKK6 to p38 and MKK7 to SAPK/JNK signaling pathways are activated in a cyclosporin A-sensitive manner and contribute to IL-2 gene expression in T lymphocytes.

ErbB-2 expression is correlated with poor prognosis for patients with osteosarcoma

BACKGROUND

It has been reported that the c-erbB-2 protooncogene is frequently amplified and overexpressed in many types of cancers, except sarcomas and hematological malignancies.

METHODS

Expression of ErbB-2 in the tumors of 26 patients with conventional osteosarcoma was evaluated by immunoblotting. DNA from osteosarcoma tissues that expressed ErbB-2 were analyzed by Southern blot hybridization to examine gross rearrangement of the gene. The DNA was also surveyed for the presence of genetic mutation in the transmembrane domain of ErbB-2 by polymerase chain reaction-single-stranded DNA conformation polymorphism analysis. In addition, possible correlation of ErbB-2 expression with gender, age, histopathologic subtype, and response to chemotherapy was analyzed. Survival analysis was performed by the Kaplan-Meier test using the approximate chi-square statistic for the log-rank test.

RESULTS

The ErbB-2 protein was detected in 11 of 26 osteosarcoma tissues (42%) by immunoblot analysis. Expression of ErbB-2 was confirmed by immunohistochemical studies using specific anti-ErbB-2 monoclonal antibody. However, neither amplification of the c-erbB-2 gene nor evidence of significant genetic mutation was found in these osteosarcomas. Expression of ErbB-2 examined by immunoblotting was most strongly correlated with early pulmonary metastases (P < 0.05). Among the entire group of 26 patients in this study, Kaplan-Meier life table survival of the patients with apparent ErbB-2 expression was significantly worse than that of the patients with little ErbB-2 expression (P < 0.01).

CONCLUSIONS

In 42% of the osteosarcomas, the tumor cells expressed ErbB-2. Expression of ErbB-2 was strongly correlated with early pulmonary metastasis and poor survival rate for the patient. These data suggest that ErbB-2 plays a significant role in aggressive tumor growth and in the promotion of metastatic potential in osteosarcomas. ErbB-2 in the osteosarcoma tissues would be a useful prognostic marker for patients.

Protection of ischemic hippocampal neurons by ginsenoside Rb1, a main ingredient of ginseng root

Our previous study showed that the oral administration of red ginseng powder before but not after transient forebrain ischemia prevented delayed neuronal death in gerbils, and that a neuroprotective molecule within red ginseng powder was ginsenoside Rb1. However, it remains to be clarified whether or not ginsenoside Rb1 acts directly on the ischemic brain, and the mechanism by which ginsenoside Rb1 protects the ischemic CA1 neurons is not determined. Without elucidation of the pharmacological property of ginsenoside Rb1, the drug would not be accepted as a neuroprotective agent. The present study demonstrated that the intracerebroventricular infusion of ginsenoside Rb1 after 3.5 min or 3 min forebrain ischemia, precluded significantly the ischemia-induced shortening of response latency in a step-down passive avoidance task and rescued a significant number of hippocampal CA1 neurons from lethal ischemic damage. The intracerebroventricular infusion of ginsenoside Rb1 did not affect hippocampal blood flow or hippocampal temperature except that it caused a slight increase in hippocampal blood flow at 5 min after transient forebrain ischemia. Furthermore, ginsenoside Rb1 at concentrations of 0.1-100 fg/ml (0.09-90 fM) rescued hippocampal neurons from lethal damage caused by the hydroxyl radical-promoting agent FeSO4 in vitro, and the Fenton reaction system containing p-nitrosodimethylaniline confirmed the hydroxyl radical-scavenging activity of ginsenoside Rb1. These findings suggest that the central infusion of ginsenoside Rb1 after forebrain ischemia protects hippocampal CA1 neurons against lethal ischemic damage possibly by scavenging free radicals which are overproduced in situ after brain ischemia and reperfusion. The present study may validate the empirical usage of ginseng root over thousands of years for the prevention of cerebrovascular diseases.

Analysis of prognostic factors in newly diagnosed acute promyelocytic leukemia treated with all-trans retinoic acid and chemotherapy. Japan Adult Leukemia Study Group

PURPOSE

We conducted a multicenter study of differentiation therapy with all-trans retinoic acid (ATRA) followed by intensive chemotherapy in patients with newly diagnosed acute promyelocytic leukemia (APL) and analyzed the prognostic factors for predicting complete remission (CR), event-free survival (EFS), and disease-free survival (DFS).

PATIENTS AND METHODS

All patients received ATRA until CR. If patients had an initial leukocyte count greater than 3.0 x 10(9)/L, they received daunorubicin (DNR) and behenoyl cytarabine (BHAC). During therapy, if patients showed blast and promyelocyte counts greater than 1.0 x 10(9)/L, they received additional DNR and BHAC. After achieving CR, patients received three courses of consolidation and six courses of maintenance/intensification chemotherapy.

RESULTS

Of 198 registered, 196 were assessable (age range, 15 to 86 years; median, 46) and 173 (88%) achieved CR. Multivariate analysis showed that no or minor purpura at diagnosis (P = .0046) and age less than 30 years (P = .0076) were favorable factors for achievement of CR. Predicted 4-year overall survival and EFS rates were 74% and 54%, respectively, and the 4-year predicted DFS rate for 173 CR patients was 62%. Multivariate analysis showed that age less than 30 years (P = .0003) and initial leukocyte count less than 10 x 10(9)/L (P = .0296) were prognostic factors for longer EFS, and initial leukocyte count less than 10.0 x 10(9)/L was a sole significant prognostic factor for longer DFS (P = .0001).

CONCLUSION

Our results show that age, hemorrhagic diathesis, and initial leukocyte count are prognostic factors for APL treated with ATRA followed by intensive chemotherapy.

Xenopus MAP kinase activator is a serine/threonine/tyrosine kinase activated by threonine phosphorylation

Xenopus MAP kinase activator, a 45 kDa protein, has been shown to function as a direct upstream factor sufficient for full activation and both tyrosine and serine/threonine phosphorylation of inactive MAP kinase. We have now shown by using an anti-MAP kinase activator antiserum that MAP kinase activator is ubiquitous in tissues and is regulated post-translationally. Activation of MAP kinase activator is correlated precisely with its threonine phosphorylation during the oocyte maturation process. It is a key question whether MAP kinase activator is a kinase or not. We have shown that Xenopus MAP kinase activator purified from mature oocytes is capable of undergoing autophosphorylation on serine, threonine and tyrosine residues. Dephosphorylation of purified activator by protein phosphatase 2A treatment inactivates its autophosphorylation activity as well as its activator activity. Thus, Xenopus MAP kinase activator is a protein kinase with specificity for both serine/threonine and tyrosine. Partial protein sequencing of purified activator indicates that it contains a sequence homologous to kinase subdomains VI and VII of two yeast protein kinases, STE7 and byrl.

Molecular cloning of the complementary DNA and gene that encode mouse brain natriuretic peptide and generation of transgenic mice that overexpress the brain natriuretic peptide gene

Brain natriuretic peptide (BNP) is a cardiac hormone that occurs predominantly in the ventricle. To study the roles of BNP in chronic cardiovascular regulation, we isolated mouse BNP cDNA and genomic clones, and generated transgenic mice with elevated plasma BNP concentration. The mouse BNP gene was organized into three exons and two introns. Two BNP mRNA species were identified, which were generated by the alternative mRNA splicing. The ventricle was a major site of BNP production in mice. Mouse preproBNP was a 121- (or 120-) residue peptide, and its COOH-terminal 45-residue peptide was the major storage form in the heart. Transgenic mice carrying the human serum amyloid P component/mouse BNP fusion gene were generated so that the hormone expression is targeted to the liver. In the liver of these mice, considerable levels of BNP mRNA and peptide were detected, reaching up to 10-fold greater than in the ventricle. These animals showed 10- to 100-fold increase in plasma BNP concentration accompanied by elevated plasma cyclic GMP concentration, and had significantly lower blood pressure than their nontransgenic littermates. The present study demonstrates that these mice provide a useful model system with which to assess the roles of BNP in cardiovascular regulation and suggests the potential usefulness of BNP as a long-term therapeutic agent.