Direct identification of the rotary angle of ATP cleavage in F1-ATPase from Bacillus PS3

F1-ATPase is the world's smallest biological rotary motor driven by ATP hydrolysis at three catalytic β subunits. The 120° rotational step of the central shaft γ consists of 80° substep driven by ATP binding and a subsequent 40° substep. In order to correlate timing of ATP cleavage at a specific catalytic site with a rotary angle, we designed a new F1-ATPase (F1) from thermophilic Bacillus PS3 carrying β(E190D/F414E/F420E) mutations, which cause extremely slow rates of both ATP cleavage and ATP binding. We produced an F1 molecule that consists of one mutant β and two wild-type βs (hybrid F1). As a result, the new hybrid F1 showed two pausing angles that are separated by 200°. They are attributable to two slowed reaction steps in the mutated β, thus providing the direct evidence that ATP cleavage occurs at 200° rather than 80° subsequent to ATP binding at 0°. This scenario resolves the long-standing unclarified issue in the chemomechanical coupling scheme and gives insights into the mechanism of driving unidirectional rotation.

Characterization of the motility of monomeric kinesin-5/Cin8

Cin8, the Saccharomyces cerevisiae kinesin-5, has an essential role in mitosis. In in vitro motility assays, tetrameric and dimeric Cin8 constructs showed bidirectional motility in response to ionic strength or Cin8 motor density. However, whether property-switching directionality is present in a monomeric form of Cin8 is unknown. Here we engineered monomeric Cin8 constructs with and without the Cin8-specific ∼99 residues in the loop 8 domain and examined the directionality of these constructs using an in vitro polarity-marked microtubule gliding assay within the range of the motor density or ionic strength. We found that both monomeric constructs showed only plus end-directed activity over the ranges measured, which suggested that minus end-directed motility driven by Cin8 is necessary for at least dimeric forms. Using an in vitro microtubule corkscrewing assay, we also found that monomeric Cin8 corkscrewed microtubules around their longitudinal axes with a constant left-handed pitch. Overall, our results imply that plus-end-directed and left-handed motor activity comprise the intrinsic properties of the Cin8 motor domain as with other monomeric N-kinesins.

CYK4 relaxes the bias in the off-axis motion by MKLP1 kinesin-6

Centralspindlin, a complex of the MKLP1 kinesin-6 and CYK4 GAP subunits, plays key roles in metazoan cytokinesis. CYK4-binding to the long neck region of MKLP1 restricts the configuration of the two MKLP1 motor domains in the centralspindlin. However, it is unclear how the CYK4-binding modulates the interaction of MKLP1 with a microtubule. Here, we performed three-dimensional nanometry of a microbead coated with multiple MKLP1 molecules on a freely suspended microtubule. We found that beads driven by dimeric MKLP1 exhibited persistently left-handed helical trajectories around the microtubule axis, indicating torque generation. By contrast, centralspindlin, like monomeric MKLP1, showed similarly left-handed but less persistent helical movement with occasional rightward movements. Analysis of the fluctuating helical movement indicated that the MKLP1 stochastically makes off-axis motions biased towards the protofilament on the left. CYK4-binding to the neck domains in MKLP1 enables more flexible off-axis motion of centralspindlin, which would help to avoid obstacles along crowded spindle microtubules.

Analysing the 3D movement of MKLP1 motors, Maruyama et al. find that dimeric C. elegans MKLP1 drives a left-handed helical motion around the microtubule with minimum protofilament switching to the right side whereas less persistent motions are driven by monomers or by heterotetramers with CYK4. These findings suggest how obstacles along crowded spindle microtubules may be avoided by CYK4 binding to MKLP1.

Circular orientation fluorescence emitter imaging (COFEI) of rotational motion of motor proteins

Single-molecule fluorescence polarization technique has been utilized to detect structural changes in biomolecules and intermolecular interactions. Here we developed a single-molecule fluorescence polarization measurement system, named circular orientation fluorescence emitter imaging (COFEI), in which a ring pattern of an acquired fluorescent image (COFEI image) represents an orientation of a polarization and a polarization factor. Rotation and pattern change of the COFEI image allow us to find changes in the polarization by eye and further values of the parameters of a polarization are determined by simple image analysis with high accuracy. We validated its potential applications of COFEI by three assays: 1) Detection of stepwise rotation of F₁-ATPase via single quantum nanorod attached to the rotary shaft γ; 2) Visualization of binding of fluorescent ATP analog to the catalytic subunit in F₁-ATPase; and 3) Association and dissociation of one head of dimeric kinesin-1 on the microtubule during its processive movement through single bifunctional fluorescent probes attached to the head. These results indicate that the COFEI provides us the advantages of the user-friendly measurement system and persuasive data presentations.

Spontaneous structural changes in actin regulate G-F transformation

Transformations between G- (monomeric) and F-actin (polymeric) are important in cellular behaviors such as migration, cytokinesis, and morphing. In order to understand these transitions, we combined single-molecule Förster resonance energy transfer with total internal reflection fluorescence microscopy to examine conformational changes of individual actin protomers. We found that the protomers can take different conformational states and that the transition interval is in the range of hundreds of seconds. The distribution of these states was dependent on the environment, suggesting that actin undergoes spontaneous structural changes that accommodate itself to polymerization.

Simultaneous observation of the lever arm and head explains myosin VI dual function

Myosin VI is an adenosine triphosphate (ATP)-driven dimeric molecular motor that has dual function as a vesicle transporter and a cytoskeletal anchor. Recently, it was reported that myosin VI generates three types of steps by taking either a distant binding or adjacent binding state (noncanonical hand-over-hand step pathway). The adjacent binding state, in which both heads bind to an actin filament near one another, is unique to myosin VI and therefore may help explain its distinct features. However, detailed information of the adjacent binding state remains unclear. Here simultaneous observations of the head and tail domain during stepping are presented. These observations show that the lever arms tilt forward in the adjacent binding state. Furthermore, it is revealed that either head could take the subsequent step with equal probability from this state. Together with previous results, a comprehensive stepping scheme is proposed; it includes the tail domain motion to explain how myosin VI achieves its dual function.

A change in the radius of rotation of F1-ATPase indicates a tilting motion of the central shaft

F(1)-ATPase is a water-soluble portion of F(o)F(1)-ATP synthase and rotary molecular motor that exhibits reversibility in chemical reactions. The rotational motion of the shaft subunit γ has been carefully scrutinized in previous studies, but a tilting motion of the shaft has never been explicitly postulated. Here we found a change in the radius of rotation of the probe attached to the shaft subunit γ between two different intermediate states in ATP hydrolysis: one waiting for ATP binding, and the other waiting for ATP hydrolysis and/or subsequent product release. Analysis of this radial difference indicates a ~4° outward tilting of the γ-subunit induced by ATP binding. The tilt angle is a new parameter, to our knowledge, representing the motion of the γ-subunit and provides a new constraint condition of the ATP-waiting conformation of F(1)-ATPase, which has not been determined as an atomic structure from x-ray crystallography.

Switch between large hand-over-hand and small inchworm-like steps in myosin VI

Many biological motor molecules move within cells using stepsizes predictable from their structures. Myosin VI, however, has much larger and more broadly distributed stepsizes than those predicted from its short lever arms. We explain the discrepancy by monitoring Qdots and gold nanoparticles attached to the myosin-VI motor domains using high-sensitivity nanoimaging. The large stepsizes were attributed to an extended and relatively rigid lever arm; their variability to two stepsizes, one large (72 nm) and one small (44 nm). These results suggest that there exist two tilt angles during myosin-VI stepping, which correspond to the pre- and postpowerstroke states and regulate the leading head. The large steps are consistent with the previously reported hand-over-hand mechanism, while the small steps follow an inchworm-like mechanism and increase in frequency with ADP. Switching between these two mechanisms in a strain-sensitive, ADP-dependent manner allows myosin VI to fulfill its multiple cellular tasks including vesicle transport and membrane anchoring.

Single molecule FRET for the study on structural dynamics of biomolecules

Single molecule fluorescence resonance energy transfer (FRET) is the technique that has been developed by combining FRET measurement and single molecule fluorescence imaging. This technique allows us to measure the dynamic changes of the interaction and structures of biomolecules. In this study, the validity of the method was tested using fluorescence dyes on double stranded DNA molecules as a rigid spacer. FRET signals from double stranded DNA molecules were stable and their average FRET values provided the distance between the donor and acceptor in agreement with B-DNA type helix model. Next, the single molecule FRET method was applied to the studies on the dynamic structure of Ras, a signaling protein. The data showed that Ras has multiple conformational states and undergoes transition between them. This study on the dynamic conformation of Ras provided a clue for understanding the molecular mechanism of cell signaling switches.

Post-secretion neutralization of transgene-derived effect: soluble erythropoietin receptor/IgG1Fc expressed in liver neutralizes erythropoietin produced in muscle

BACKGROUND

The regulation of transgene expression is a key issue for the development of safe gene therapy. Various strategies have been used to regulate protein production at the levels of transgene expression, transcription, translation, and secretion. Neutralization following secretion is another important backup system to prevent super-therapeutic levels of a protein from being expressed by gene transfer.

METHODS

We tested whether the soluble human erythropoietin receptor (EpoR)/IgG(1)Fc could neutralize the rat Epo at the post-secretory level and suppress erythrocytosis.

RESULTS

To assess whether soluble human EpoR could bind rat Epo in vitro, we used the Epo-dependent human leukemic cell line, AS-E2. EpoR/IgG(1)Fc significantly inhibited the growth of AS-E2 cells in Epo-containing medium. To test this neutralization effect of EpoR/IgG(1)Fc in vivo, we first transferred pCAGGS-Epo into rat muscle by in vivo electroporation, confirmed erythropoiesis for 3 weeks, and then delivered EpoR/IgG(1)Fc by liver-targeted gene transfer via tail-vein injection with hydrodynamics-based transfection. Reticulocyte counts and hematocrit levels in rats that received pCAGGS-EpoR/IgG(1)Fc injections were significantly lower than in rats that received pCAGGS-EpoR, pCAGGS-IgG(1)Fc, or no injection.

CONCLUSIONS

These results demonstrate that liver-targeted pCAGGS-EpoR/IgG(1)Fc transfer by tail-vein injection with hydrodynamics-based transfection is useful for neutralizing Epo delivered by in vivo electroporation. This backup strategy at the level of post-secretion could facilitate the clinical application of gene therapy in the future.

High-level expression of naked DNA delivered to rat liver via tail vein injection

BACKGROUND

High levels of foreign gene expression in mouse hepatocytes can be achieved by rapid tail vein injection of a large volume of a naked DNA solution, the 'hydrodynamics-based procedure'. Rats are more tolerant of the frequent phlebotomies required for monitoring blood parameters than mice, and thus are better for some biomedical research.

METHODS

We tested this technique for the delivery of a therapeutic protein in normal rats, using a rat erythropoietin (Epo) expression plasmid vector, pCAGGS-Epo.

RESULTS

We obtained maximal Epo expression when the DNA solution was injected in a volume of 25 ml (approximately 100 ml/kg body weight) within 15 s. We observed a dose-response relationship between serum Epo levels and the amount of injected DNA up to 800 microg. Using quantitative real-time PCR, the vector-derived Epo mRNA expression was mainly detected in the liver. When a lacZ expression plasmid was injected similarly, beta-galactosidase was exclusively detected in the liver, mainly in hepatocytes. Toxicity attributable to the technique was mild and transient, as assessed by histochemical analysis. Epo gene expression and erythropoiesis occurred with Epo gene transfer in a dose-dependent manner, and persisted for at least 12 weeks, the last time point examined. Repeated administration of the plasmid DNA also effectively led to erythropoiesis.

CONCLUSIONS

These results demonstrate that gene transfer into the liver via rapid tail vein injection can easily be achieved in the rat, which is more than 10 times larger than the mouse, and has significant value for gene function analysis in rats.

Carcinosarcoma of the uterus: immunohistochemical and genetic analysis of clonality of one case

BACKGROUND

Carcinosarcomas of the uterus are characterized by admixtures of malignant epithelial and stromal cells, and their histogenesis remains controversial.

CASE

An operated case of carcinosarcoma of the uterus in a 49-year-old woman is reported with clonal analysis. The tumor was composed of carcinomatous, sarcomatous, and transitional elements in the frontal wall of the uterine body and therefore was diagnosed as a carcinosarcoma. On immunohistochemical analysis, the sarcomatous component proved negative for epithelial membrane antigen and keratin while both components were positive for vimentin. Analysis of X-chromosome inactivation showed the same pattern throughout and additionally, the same K-ras and p53 mutations were homogeneously detected. Microsatellite instability analysis showed loss of heterozygosity at D5S346 in the sarcomatous but not the carcinomatous component.

CONCLUSIONS

This tumor appears monoclonal in line with the combination tumor theory, with late divergence in genetic alteration in the sarcomatous elements.

Long-term production of erythropoietin after electroporation-mediated transfer of plasmid DNA into the muscles of normal and uremic rats

The anemia associated with chronic renal failure is one of the best target diseases for erythropoietin (Epo) gene transfer. We previously reported a short-term (1 month) study of continuous rat Epo delivery by muscle-targeted gene transfer of plasmid DNA expressing rat Epo (pCAGGS-Epo) using in vivo electroporation in normal rats. Here, we performed a long-term pharmacokinetic study of continuous Epo delivery by this method in normal rats and uremic five-sixths nephrectomized rats. In normal rats, Epo gene expression and sufficient erythropoiesis occurred with Epo gene transfer in a dose-dependent manner, and persisted for at least 11 weeks. Repeated administration of the plasmid DNA effectively produced erythropoiesis. Similar erythropoiesis was observed in the uremic rats, and persisted for more than 15 weeks. Both normal and uremic rats showed a significant decrease in platelet count. Moreover, the uremic rats showed Epo-induced hypertension, which is the major side-effect of recombinant human Epo. These results demonstrate that muscle-targeted pCAGGS-Epo transfer by in vivo electroporation is a useful procedure for the long-term continuous delivery of Epo in both normal and uremic rats.

Five cases of Diphyllobothrium nihonkaiense infection with discovery of plerocercoids from an infective source, Oncorhynchus masou ishikawae

Five persons from 2 families residing at Miyama Town, Mie Prefecture, Japan, ingested fresh raw fish Oncorhynchus sp. on 9 May 1999 that was caught at Owase district in Mie. They all expelled diphyllobothriid cestodes 11-37 days after ingesting the fish. The parasites were morphologically identical to Diphyllobothrium nihonkaiense Yamane et al., 1986. Five plerocercoids were detected from a portion of the fish. Nucleotide sequence of a region of the cytochrome c oxidase subunit I gene of mitochondrial DNA from an adult worm was identical with that from the plerocercoid. The fish was identified as Oncorhynchus masou ishikawae according to the nucleotide sequence of the nuclear ribosomal second internal transcribed spacer region II gene. This is the first record of D. nihonkaiense plerocercoids from O. m. ishikawae.

Continuous erythropoietin delivery by muscle-targeted gene transfer using in vivo electroporation

It has been demonstrated that gene transfer by in vivo electroporation of mouse muscle increases the level of gene expression by more than 100-fold over simple plasmid DNA injection. We tested continuous rat erythropoietin (Epo) delivery by this method in normal rats, using plasmid DNA expressing rat Epo (pCAGGS-Epo) as the vector. A pair of electrodes was inserted into the thigh muscles of rat hind limbs and 100 microg of pCAGGS-Epo was injected between the electrodes. Eight 100-V, 50-msec electric pulses were delivered through the electrodes. Each rat was injected with a total of 400 microg of pCAGGS-Epo, which was delivered to the medial and lateral sides of each thigh. The presence of vector-derived Epo mRNA at the DNA injection site was confirmed by RT-PCR. The serum Epo levels peaked at 122.2 +/- 33.0 mU/ml on day 7 and gradually decreased to 35.9 +/- 18.2 mU/ml on day 32. The hematocrit levels increased continuously, from the preinjection level of 49.5 +/- 1.1 to 67.8 +/- 2.2% on day 32 (p < 0.001). In pCAGGS-Epo treated rats, endogenous Epo secretion was downregulated on day 32. In a control experiment, intramuscular injection of pCAGGS-Epo without subsequent electroporation did not significantly enhance the serum Epo levels. These results demonstrate that muscle-targeted pCAGGS-Epo transfer by in vivo electroporation is a useful procedure for the continuous delivery of Epo.

Association of remnant-like particle cholesterol with coronary artery disease in patients with normal total cholesterol levels

BACKGROUND

Limited information is available as to whether there is a difference in the association of lipid and fibrinolytic variables with coronary artery disease according to the presence or absence of elevated serum total cholesterol. We examined the levels of various lipid and fibrinolytic variables including remnant-like particle cholesterol (RLP-C). RLP-C is a recently established simple assay method for the estimation of triglyceride-rich lipoprotein remnants.

METHODS AND RESULTS

Levels of total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL-C), triglyceride, lipoprotein(a), RLP-C, uric acid, blood glucose, tissue plasminogen activator, tissue plasminogen activator inhibitor type 1, antithrombin III, and protein C were measured in 208 patients who underwent diagnostic coronary angiograms. Of these 208 patients, 57 were hypercholesterolemic (> or =220 mg/dL) and 151 were normocholesterolemic. HDL-C showed significant differences between patients with and those without angiographically determined coronary artery stenosis in both hypercholesterolemic and normocholesterolemic patients (P =.0025 and P =.0003, respectively). Both RLP-C and uric acid showed significant differences only in the normocholesterolemic subgroup (P =.0006 and P =.0060, respectively). This difference in uric acid was not significant by multivariable analysis. The ratio of RLP-C/HDL-C was demonstrated to be highly significantly (P <.0001) associated with coronary artery stenosis in patients with normal total cholesterol, whereas there was no statistically significant association in the hypercholesterolemic patient subgroup.

CONCLUSIONS

Our current study disclosed that RLP-C levels are strongly associated with coronary artery disease, especially in patients with normal total cholesterol levels. Moreover, RLP-C/HDL-C ratio may be even more significantly associated with the presence of coronary artery stenosis in normocholesterolemic patients.

Predictive value of remnant-like particles cholesterol/high-density lipoprotein cholesterol ratio as a new indicator of coronary artery disease

BACKGROUND

There is as yet no definite consensus on the predictive value of the various lipid profiles and fibrinolytic parameters that became available in clinical use recently for coronary artery disease.

METHODS

Levels of lipoprotein(a), high-density lipoprotein cholesterol (HDL-C), remnant-like particles cholesterol (RLP-C), tissue plasminogen activator (TPA), TPA inhibitor, antithrombin III, and protein C were measured in 124 patients who underwent diagnostic coronary angiograms.

RESULTS

Of these patients, 37 had no significant stenoses (group N) and 87 had significant stenoses (group S). There were no significant differences in patient characteristics between the two groups. HDL-C was significantly lower (p = 0.0071 ) and RLP-C was significantly higher (p = 0.0022) in group S. When a product and a ratio of each of two factors were calculated, RLP-C/HDL-C was demonstrated to be a highly significant predictor for coronary artery stenoses (p < 0.0001). There were also significant increases in RLP-C/HDL-C levels with increasing number of vessels involved (r = 0.359, p < 0.0001 ).

CONCLUSION

Our present study disclosed the predictive value of RLP-C/HDL-C ratio as a new indicator of coronary artery disease.

Rhabdomyolysis and myocardial damage induced by palytoxin, a toxin of blue humphead parrotfish

A 55-year-old man had rhabdomyolysis and myocardial damage induced by palytoxin. Weakness and myalgia of four extremities occurred five hours after eating a fish. Rhabdomyolysis developed and the serum creatine phosphokinase (CK) was elevated to 40,000 IU/l on the 3rd day. Gastric lavage with activated charcoal and forced mannitol-alkaline diuresis therapy were performed. The patient recovered with no complication such as renal failure. In this case, palytoxin was suggested to induce myocardial damage which was demonstrated by an elevation of the myosin light chain level and a change in electrocardiogram.

Enhancement of neurite outgrowth by the soluble form of human L1 (neural cell adhesion molecule)

L1, a neural cell adhesion molecule, is involved in neurite outgrowth, migration and fasciculation. Although L1 is a membrane glycoprotein expressed on neural cells, the soluble form of L1 is generated in vivo by proteolysis. In the present study, a stable transfectant of Chinese hamster ovary (CHO) cells secreting human L1 without cytoplasmic and membrane spanning domains was generated, and the function of the secreted L1 was examined. Explants from embryonic chick brain stem were cultured on a substrate coated with polyethylenimine (PEI) alone, on substrate-bound L1 or in medium containing soluble L1. The neurites induced by L1, both the substrate-bound form and the soluble form, were 2-3 times longer than those cultured on PEI. The ability of the soluble L1 to induce neurite formation was slightly greater than that of the substrate L1. The present results demonstrated that neurite outgrowth was induced not only by substrate-bound L1 but also by soluble L1. Soluble L1 could be a pharmaceutical candidate for the promotion of nerve regeneration.

Oxidized low density lipoprotein caused CNS neuron cell death

Death induced by oxidized low density lipoproteins (oxLDL) to embryonic CNS neuronal and neuroblastoma cells was investigated. Cell damage and viability were evaluated by LDH leakage and the MTT method, respectively. Dose- and time-dependent degeneration of neurons occurred after oxLDL (1-100 microg/ml) treatment but was absent after native low density lipoproteins (LDL). This degeneration was mediated, in part, by apoptosis because increased TUNEL and Hoechst dye-positive staining was observed. These effects occurred in the absence of microglia. However, DNA degradation was not detected. The cytotoxicity was attenuated by pre-treatment with antioxidants. These results suggest that oxidation by oxLDL may be important in neurocytotoxicity in the brain.

Axonal growth-related cell surface molecule, neurin-1, involved in neuron-glia interaction

We purified and characterized a novel axonal growth-related molecule, neurin-1, which is anchored to the surface membrane via a phosphatidylinositol (PI) linkage. This molecule was detected by a combination of phosphatidylinositol-specific phospholipase C (PI-PLC) treatment from detergent-soluble mouse brain membranes and subsequent Western blot analysis with monoclonal antibody (MAb 2A). Neurin-1 is immunologically distinct from other known axonal growth associated surface glycoproteins. In immunoblots of embryonic mouse brain membrane, the MAb 2A recognized a single band at approximately 68 kDa, and showed that neurin-1 is mainly associated with fiber-containing regions of developing embryonic mouse brain. Expression is immunohistochemically similar to that of cell adhesion molecule L1, but in comparison, neurin-1 appears somewhat later. Late in embryonic development, neurin-1 appeared to be more stage- and region-specific. Its precise localization at the neural cell surface membranes was confirmed by immuno-electron microscopy using labeled and cultured live nerve cells. Neurin-1 was found only on the surface of the axon and growth cone. Neurin-1, otherwise termed PI anchor protein, corresponds closely in function to the other PI-anchored cell adhesion molecules. Anti-neurin-1 antibody (MAb 2A), however, perturbs the axonal growth and neural cell migration from the astrocyte feeder layer cultures. These results suggest that neurin-1 is one of the important cell surface molecules mediated in the neuron and glial cell interaction.

Impaired plasticity of neurons in aging. Biochemical, biophysical, and behavioral studies

Age-related correlation of impaired plasticity of neurons (biochemical and biophysical aspects) and behavioral alterations were investigated in young (3.5 months) and extremely aged (approximately 40 months) female Wistar rats. Age-dependent significant differences in second messenger (cAMP and Ins (1,4,5)P3) concentration and signal transduction via muscarinic and dopaminergic receptors were found. The results point to the specifically impaired coupling between dopamine D1 receptor and GS protein, which underlies normal brain aging. However, cholinergic neurotransmission may be modulated at another level in extremely aged rats. Thus, it appears that the site of affection in coupling of receptor and G protein and/or G protein-dependent signal transduction in aging cannot be generalized. This indicates that alterations in the coupling of signal transduction depend on diverse neurotransmitter receptors with advanced age. The age-dependent alterations in the cAMP and PI signal pathways could be due to changes in the physical properties of the membranes. To support this hypothesis, age-dependent changes in the physical state and the biochemical composition of synaptosomal membranes from the cortex, cerebellum, and striatum were examined by measuring the steady-state fluorescence amisotropy of the membrane probes 1,6-diphenyl-1,3,5-hexatriene (DPH), trimethylammonium-DPH (TMA-DPH), and trimethylammoniumpropyl-DPH (TMAP-DPH). Significant differences in the physical properties of the synaptosomal membranes existed between young and very aged rats, expressed by a higher anisotropy in the 40-month-old rat brain tissue. The changes in the physical properties of the membranes were in line with the determined age-dependent alterations in the chemical composition, e.g., the increase in cholesterol content of the aged membranes.

Alterations of inositol phosphate turnover in striatum of aged rats

Age-related inositol phosphate turnover in the rat central nervous system was investigated. Higher phospholipase-C activity and drastically higher (almost 2.5-fold) inositol 1,4,5-trisphosphate concentration in the corpus striatum (caudate-putamen) of extremely old (approximately 40 months) female Wistar rats in comparison to the young adult (approximately 3.5 months) rats were observed. Dopamine seems to slightly inhibit total inositol phosphate formation and this effect was antagonized by (-)-sulpiride.

Age-related alteration in signal transduction: involvement of the cAMP cascade

In the present study, we have investigated the involvement of the cAMP signal transduction pathways in young and aged rats. A significantly higher endogenous adenosine 3':5'-cyclic monophosphate (cAMP) level and a significant decline of the adenylate cyclase [AC, ATP pyrophosphate-lyase (cyclizing), EC.4.6.1.1.] activity were observed in striatal tissue from young rats (3 months) in comparison to aged rats (approximately 40 months). In the nucleus accumbens (NA), no age-dependent changes in the cAMP concentration and in the AC basal activity were found. To address the question, whether the interactions of guanine nucleotide-binding protein (G-protein) subunits (G alpha s and Gi) with AC have changed in the aging process, various pharmacological agents that modulate the AC activity (e.g., beta, tau-imidoguanine 5'-triphosphate (GppNHp), sodium fluoride (NaF), forskolin (FSK), and the combinations of GppNHp plus FSK, NaF plus FSK, and NaF plus ethanol (ETOH)) were applied. In addition, a [3H]FSK binding test was carried out. In striatal and NA tissue, the stimulation of the AC activity by FSK was inhibited by GppNHp (via Gi-protein) and was superadditive by the combination of FSK and NaF (via Gs-protein). The absolute AC activity upon stimulation by all agents used was significantly lower in the aged striatum compared to young striatum. In the NA, however, the AC activity showed an age-dependent reduction only upon FSK and upon FSK plus GppNHp stimulation. There was no difference in the specific [3H]FSK binding to the G alpha s protein-coupled catalytic subunit of the AC between young and aged animals both in the striatum and NA.(ABSTRACT TRUNCATED AT 250 WORDS)

Functional roles of cyclic guanosine 3',5'-monophosphate analogue in cerebral vasodilation

1. Vasodilating effects of cyclic nucleotides in cerebral vasculature were examined using membrane permeable cyclic nucleotide analogues, 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP) and 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP). 2. In isolated canine basilar artery (CBA), 8-Br-cGMP but not 8-Br-cAMP, significantly inhibited Ca(2+)-induced and agonist [serotonin(5-HT), prostaglandin(PG)F2 alpha or endothelin]-induced contraction, in a concentration-dependent manner. 3. When Ca2+ was depleted from intracellular store sites by pretreatment with A23187, 8-Br-cGMP but not 8-Br-cAMP strongly attenuated contractions induced by Ca(2+)-influx. 4. Neither 8-Br-cGMP nor 8-Br-cAMP modified contraction induced by caffeine which elicits Ca2+ release from intracellular Ca2+ store. 5. 8-Br-cGMP lowered the high K(+)-induced sustained [Ca2+]i elevation. 6. These results suggest that, at least in CBA, cGMP exerts its inhibitory effect on the contraction induced by influx of Ca2+, by reducing the level of [Ca2+]i and reducing [Ca2+]i sensitivity of the contractile machinery.

Altered dopamine receptor mediated signal transmission in the striatum of aged rats

Striatal membranes of very old (40 months) as against young (3 months) female Wistar rats were used. Binding saturation experiments with [3H]SCH 23390 at the dopamine (DA) D1 receptor (D1) and [3H]spiperone at the DA D2 receptor (D2) revealed no change in the affinity (Kd) but a significant decrease in the density (Bmax) of D1 (-31%, P < 0.005) and of D2 (-22%, P < 0.05), respectively, in the aged vs. young striata. Displacement of either [3H]SCH 23390 or [3H]spiperone binding by DA displayed biphasic curves. The Hill coefficient (nH) was significantly increased in the senescent compared with the young of D1 (0.72 +/- 0.04 vs. 0.61 +/- 0.03, P < 0.025) but unchanged of D2 (0.49 +/- 0.04 vs. 0.51 +/- 0.02). The proportion of the high-affinity agonist binding state (Rhigh) was significantly decreased (P < 0.025) in the older (20.9 +/- 3.2%) in comparison with the young (30.6 +/- 2.0%) in D1 but increased non-significantly in D2 (47.9 +/- 2.6 vs. 40.5 +/- 5.1%). Calculating the resulting Bmax from Scatchard and displacement analyses of each single aged and young animal revealed a highly significant reduction (P < 0.001) of the high-affinity agonist binding state of D1 (-53%) as well as a non-significant reduction of D2 (-8%) in the older. Simultaneously, a significant 57% decrease (P < 0.01) in the adenylate cyclase (AC) activity stimulated by 10 microM DA in the senescent compared with the young animals was monitored. The DA stimulation of AC was reversed in both cases by the addition of 200 nM of the D1 antagonist SCH 23390.

BY-1949 elicits vasodilation via preferential elevation of cyclic GMP levels within the cerebral artery: possible involvement of endothelium-mediated mechanisms

The pharmacological mechanisms by which BY-1949, a novel dibenzoxazepine derivative, increases in regional cerebral blood flow, were investigated using the canine basilar artery in vitro. BY-1949 inhibited contractions elicited by serotonin (5-HT), prostaglandin (PG) F2 alpha, endothelin and phorbol-12,13-diacetate (PDA), respectively, to the same extent. In addition, pretreatment of the artery with methylene blue significantly suppressed the vasodilating effect of BY-1949. BY-1949 also dose dependently suppressed contractions of the basilar artery induced by CaCl2 (Ca2+) in a non-competitive manner. Biochemical studies disclosed that BY-1949 significantly increased cyclic GMP without causing any apparent change in cyclic AMP. These increases in cyclic GMP were virtually abolished after the endothelial cells were removed. These results strongly suggest that the increased regional cerebral blood flow induced by BY-1949 is explicable, at least partly, in terms of a preferential elevation of cyclic GMP within the cerebral vasculature, where the endothelium plays a pivotal role.

Activation of the protein kinase C-mediated contractile system in canine basilar artery undergoing chronic vasospasm

We previously suggested that activation of the protein kinase C-mediated contractile system may participate in the occurrence of chronic cerebral vasospasm. In the present study, we compared segments of normal beagle basilar arteries in vitro with segments of arteries undergoing chronic vasospasm to determine the responsiveness to various agonists such as serotonin, prostaglandin F2 alpha, and phorbol 12,13-diacetate as well as to external Ca2+. We also compared the effects of W-7 (a calmodulin inhibitor), nicardipine (a calcium channel blocker), and H-7 (a protein kinase C inhibitor) on the spontaneous tonus of arterial segments stabilized at a resting tension of 3 g. Compared with normal segments, the responsiveness to each agonist in segments undergoing vasospasm was essentially unchanged whereas the the responsiveness to external Ca2+ was significantly decreased (p less than 0.001). In segments undergoing vasospasm the decrease in resting tension induced by W-7 was markedly diminished (p less than 0.01), that induced by nicardipine was unchanged, and that induced by H-7 was significantly increased (p less than 0.01). Our results indicate that spontaneous tonus due to activation of the protein kinase C system is significantly augmented in segments undergoing vasospasm. Thus this system, rather than the Ca2+/calmodulin system, appears to play a major role in the occurrence of chronic vasospasm.

The role of cGMP in the anti-aggregating properties of BY-1949, a novel dibenzoxazepine derivative

The anti-aggregatory activity of a novel agent, BY-1949, 3-methoxy-11-methyldibenz (b,f) (1,4) oxazepine-8-carboxylic acid, was examined using rabbit platelets. Oral administration of BY-1949 (10 or 30 mg/kg) inhibited platelet aggregation induced by ADP, collagen, and arachidonate in a dose-related fashion. In in vitro studies, however, neither BY-1949 nor its major metabolites inhibited platelet aggregation, even at a concentration similar to that attained in plasma in vivo. With regard to the anti-aggregatory action of BY-1949, biochemical analysis revealed that BY-1949 preferentially augmented cyclic GMP (cGMP) formation, via inhibition of phosphodiesterase activity, without altering cyclic AMP (cAMP) formation. Furthermore, the in vitro anti-aggregatory activity was significantly enhanced when the platelets were concomitantly treated with nitric oxide (NO). Based on these results, it is suggested that the in vivo anti-aggregatory effects of BY-1949 are at least partly elicited via platelet/endothelium interactions, in which cGMP plays a pivotal role.

Phorbol 12,13-diacetate-induced contraction of the canine basilar artery: role of protein kinase C

The pharmacological and biochemical mechanisms of contractile responses to the protein kinase C (PKC) activator phorbol-12,13-diacetate (PDA) were investigated in canine basilar arteries. In the normal medium, PDA elicited a strong, dose-related, and slow-developing sustained contraction. Among the constrictors examined, including serotonin, prostaglandin F2 alpha, and endothelin, only PDA yielded contractions in a Ca2(+)-free medium. In both media, the PDA-induced contractions were virtually inhibited by either staurosporine, H-7, or quinacrine, while neither neurotransmitter blockades nor R24571 (calmidazolium) exerted significant effects. In addition, it was shown that 8-bromocyclic GMP, but not 8-bromocyclic AMP, markedly curtailed the PDA-induced contractions. Biochemical analysis, furthermore, showed that PDA induced increased phosphorylations of 27- and 96-kDa and proteins other than the myosin light chain (MLC) 20-kDa protein. Thus, the present results open up a novel mechanism of sustained cerebral artery contractions, where PKC activation rather than Ca2+/calmodulin/MLC system plays a key role that is regulated both by phospholipase A2 and by cyclic GMP.

A case of tuberculous pericarditis--use of adenosine deaminase activity (ADA) in early diagnosis

Pericardial tuberculosis is rare, and because of the difficulty in isolating the causative organism, the diagnosis is often missed. Adenosine deaminase, an enzyme associated with purine metabolism, shows markedly high levels of activity in tuberculous effusion. We report a case of tuberculous pericarditis diagnosed by high levels of adenosine deaminase activity, and where the pericardial fluid cultures revealed acid-fast organisms.

[Effects of BY-1949 on three kinds of experimental amnesia in rodents]

The possible anti-amnesic effects of a dibenzoxazepine derivative, BY-1949 (3-methoxy-11-methyldibenz[b,f] [1, 4] oxazepine-8-carboxylate), were examined using the three learning paradigms. In the one-trial passive avoidance task in mice, BY-1949 (1-30 mg/kg, po) and aniracetam (3-30 mg/kg, po) reversed the shortening of the response latency in the retention test produced by exposure to 100% CO2 immediately after the acquisition trial. In the two-way active avoidance task in rats, BY-1949 (10, 30 mg/kg, po) reversed the decreased avoidance rate produced by the hypoxia treatment (5% O2:95% N2). In the radial-arm maze task in rats, BY-1949 (10 mg/kg, po) and aniracetam (10, 30 mg/kg, po) improved the impaired correct choices induced by scopolamine (0.25 mg/kg, ip). These results suggest that BY-1949, as well as aniracetam, exerts some improvement effects on experimental amnesia.

Assessment of mitral regurgitation using gated radionuclide ventriculography: analysis of left atrial time activity curve

The authors analyzed the left atrial (LA) time activity curve (TAC) in 18 normal subjects and 30 patients with mitral regurgitation (MR) to assess the usefulness of radionuclide ventriculography (RNV) in detecting MR. The LA TAC was generated from gated blood pool images using phase and amplitude images. The configuration of normal LA TAC was M shaped. The first peak and last peak of LA TAC were represented as points B and D, respectively. In addition, the trough following B was named point C. The presence and severity of MR was analyzed by use of three methods: (1) analysis of LA TAC, (2) analysis of left ventricular TAC, and (3) measurement of the stroke count ratio of left ventricle to right ventricle. In the diagnosis of MR using RNV, the rapid emptying fraction [REF:(B-C)/(B-A)] of LA TAC was the most sensitive index compared with the other two methods. The sensitivity and specificity of MR with Sellers' II degrees or more were 0.84 and 0.90 in LA TAC but were 0.42 and 0.90 in the count method.

A novel dibenzoxazepine derivative (BY-1949) increases regional cerebral blood flow

The effects of BY-1949, a novel dibenzoxazepine derivative, on the regional cerebral blood flow were investigated in conscious cats. Oral administration of BY-1949 (10-50 mg/kg) significantly increased in a dose-related manner the regional cerebral blood flow in all brain regions examined. Vinpocetine (20 mg/kg p.p.) had similar effects that were shorter-lasted than those of BY-1949. From these results, it seems likely that amelioration by BY-1949 of cognitive impairment following cerebral ischemia/hypoxia or that occurs on ageing is at least partly explainable in terms of its effects on the cerebral circulation.

A case of infectious pseudoaneurysm of the abdominal aorta associated with infectious spondylitis due to Klebsiella pneumoniae

A 67-year-old woman with pneumonia and diabetes mellitus was admitted with the complaints of abdominal and back pain. Sputum culture was positive for Klebsiella pneumoniae. Computed tomographic scanning (CT) of the abdomen and spinal radiograph of the lumber column revealed a paraventebral space-occupying lesion, abdominal aortic aneurysm and destructive change of L3 and L4. Pseudoaneurysm of the abdominal aorta associated with infectious spondylitis with paravertebral abscess was suspected and confirmed by aortography. Klebsiella pneumoniae was cultured from the abscess. The patient's condition improved rapidly after drainage of the abscess and administration of LMOX and gentamicin. Infectious pseudoaneurysm of the abdominal aorta associated with infectious spondylitis has rarely been reported. These two in combination due to Klebsiella pneumoniae has not been reported to our knowledge. The pathologic changes were found easily by CT scan. When infectious aneurysm or infectious spondylitis is diagnosed alone, possible combination of these diseases should be kept in mind.

Successful fibrinolytic treatment for recurrent thrombosis on aortic valve prosthesis

A 15-year-old girl with a prosthetic aortic valve had recurrent episodes of prosthetic valve thrombosis. She had had an emergency operation that included aortic valve replacement because of congestive heart failure secondary to aortic regurgitation due to annuloaortic ectasia complicated by aortitis syndrome. She had been on warfarin. On each admission, fibrinolytic therapy was given to her because she refused reoperation. The therapy was successful and without any complications. After the Thrombotest index was controlled between 6% and 15%, prosthetic valve thrombosis did not recur. The values of beta-thromboglobulin and platelet factor 4 were also kept within the normal range. We concluded that: (1) in circumstances that prevented surgery, fibrinolytic therapy was successful. (2) Adequate anticoagulant therapy prevented recurrence of prosthetic valve thrombosis. (3) Elevations of beta-thromboglobulin and platelet factor 4 proved to be diagnostic indicators for prosthetic valve thrombosis.