An orally active cathepsin K inhibitor, furan-2-carboxylic acid, 1-{1-[4-fluoro-2-(2-oxo-pyrrolidin-1-yl)-phenyl]-3-oxo-piperidin-4-ylcarbamoyl}-cyclohexyl)-amide (OST-4077), inhibits osteoclast activity in vitro and bone loss in ovariectomized rats

Human cathepsin K, a cysteine proteinase of the papain family, has been recognized as a potential drug target for the treatment of osteoporosis. The predominant expression of cathepsin K in osteoclasts has rendered the enzyme into a major target for the development of novel antiresorptive drugs. Now, we report the pharmacological properties of OST-4077 [furan-2-carboxylic acid (1-{1-[4-fluoro-2-(2-oxo-pyrrolidin-1-yl)-phenyl]-3-oxo-piperidin-4-ylcarbamoyl}-cyclohexyl)-amide] as a novel selective cathepsin K inhibitor. Human and rat cathepsin K were inhibited in vitro by OST-4077 with the IC50 values of 11 and 427 nM, respectively. OST-4077 suppressed bone resorption induced by rabbit osteoclasts (IC50, 37 nM) but did not affect bone mineralization or cellular alkaline phosphatase activity in MC3T3-E1 cells. Parathyroid hormone-induced bone resorption was inhibited in a dose-dependent manner in thyroparathyroidectomized rats gavaged with a single dose of OST-4077 (ED50, 69 mg/kg). When given orally twice daily for 4 weeks to 3-month-old ovariectomized (OVX) rats, OST-4077 dose-dependently prevented bone loss, as monitored by bone densitometry, ash content, and urinary excretion of deoxypyridinoline. No change in serum osteocalcin in the OVX rats by OST-4077 suggested that bone formation might not be affected by the agent. In summary, OST-4077 selectively inhibited bone resorbing activities of osteoclasts and prevented bone loss induced by estrogen deficiency but did not affect bone formation. OST-4077, an orally active selective human cathepsin K inhibitor, may have the therapeutic potential for the treatment of diseases characterized by excessive bone loss including osteoporosis.

Exploratory activity and spatial learning in 12-month-old APP695SWE/co+PS1/ΔE9 mice with amyloid plaques

APP(695)SWE/co+PS1/DeltaE9 mice with Abeta plaques in neocortex and hippocampus were evaluated in tests of exploratory activity and spatial learning. On the initial testing day, 12-month-old APP(695)SWE/co+PS1/DeltaE9 mice spent more time than non-transgenic controls in the open arms of the elevated plus-maze. The bigenic group also travelled farther in the central region of the open-field without spending more time there. Only the bigenic group alternated above chance in the T-maze. In the Morris water maze, APP(695)SWE/co+PS1/DeltaE9 mice were impaired during acquisition of the hidden platform sub-task and the probe trial but not in the visible platform test. These results indicate a selective spatial deficit and disinhibitory tendencies in a mouse model with amyloid pathology.

Production of the neutron-rich hypernucleus 10LambdaLi in the (pi-,K+) double charge-exchange reaction

In order to produce a neutron-rich Lambda hypernucleus for the first time, we carried out an experiment by utilizing the (pi-,K+) double charge-exchange reaction on a 10B target. We observed the production of a 10LambdaLi hypernucleus. The cross section for the Lambda bound region was found to be 11.3+/-1.9 nb/sr with the 1.2 GeV/c incident momentum, which is compared with the 10LambdaB hypernucleus production cross section, 7.8+/-0.3 microb/sr, in the (pi+,K+) reaction with a 1.05 GeV/c incident momentum beam.

Site-specific labeling of the ribosome for single-molecule spectroscopy

Single-molecule fluorescence spectroscopy can reveal mechanistic and kinetic details that may not be observed in static structural and bulk biochemical studies of protein synthesis. One approach requires site-specific and stable attachment of fluorophores to the components of translation machinery. Fluorescent tagging of the ribosome is a prerequisite for the observation of dynamic changes in ribosomal conformation during translation using fluorescence methods. Modifications of the ribosomal particle are difficult due to its complexity and high degree of sequence and structural conservation. We have developed a general method to label specifically the prokaryotic ribosome by hybridization of fluorescent oligonucleotides to mutated ribosomal RNA. Functional, modified ribosomes can be purified as a homogenous population, and fluorescence can be monitored from labeled ribosomal complexes immobilized on a derivatized quartz surface.

Exploratory activity, anxiety, and motor coordination in bigenic APPswe + PS1/ΔE9 mice

Bigenic APPswe + PS1/DeltaE9 mice with Abeta plaque formation in neocortex and hippocampus were evaluated in three tests measuring exploratory activity. By comparison to a non-transgenic group controlled for age and gender, 7-month-old APPswe + PS1/DeltaE9 mice spent more time in the open arms and had higher open/total entries and duration in the elevated plus-maze, indicative of disinhibitory tendencies. On the contrary, the groups did not differ in T-maze and open-field tests. Moreover, the motor coordination of the bigenic group was equivalent to that of controls in stationary beam, coat-hanger, rotorod, and grip strength tests. No mouse displayed neurological signs, such as pathological reflexes, myoclonus, or convulsions. The results in the elevated plus-maze test are akin to the loss of inhibitory control observed in some patients with Alzheimer's disease.

tRNA selection and kinetic proofreading in translation

Using single-molecule methods we observed the stepwise movement of aminoacyl-tRNA (aa-tRNA) into the ribosome during selection and kinetic proofreading using single-molecule fluorescence resonance energy transfer (smFRET). Intermediate states in the pathway of tRNA delivery were observed using antibiotics and nonhydrolyzable GTP analogs. We identified three unambiguous FRET states corresponding to initial codon recognition, GTPase-activated and fully accommodated states. The antibiotic tetracycline blocks progression of aa-tRNA from the initial codon recognition state, whereas cleavage of the sarcin-ricin loop impedes progression from the GTPase-activated state. Our data support a model in which ribosomal recognition of correct codon-anticodon pairs drives rotational movement of the incoming complex of EF-Tu-GTP-aa-tRNA toward peptidyl-tRNA during selection on the ribosome. We propose a mechanistic model of initial selection and proofreading.

tRNA dynamics on the ribosome during translation

Using single-molecule fluorescence spectroscopy, time-resolved conformational changes between fluorescently labeled tRNA have been characterized within surface-immobilized ribosomes proceeding through a complete cycle of translation elongation. Fluorescence resonance energy transfer was used to observe aminoacyl-tRNA (aa-tRNA) stably accommodating into the aminoacyl site (A site) of the ribosome via a multistep, elongation factor-Tu dependent process. Subsequently, tRNA molecules, bound at the peptidyl site and A site, fluctuate between two configurations assigned as classical and hybrid states. The lifetime of classical and hybrid states, measured for complexes carrying aa-tRNA and peptidyl-tRNA at the A site, shows that peptide bond formation decreases the lifetime of the classical-state tRNA configuration by approximately 6-fold. These data suggest that the growing peptide chain plays a role in modulating fluctuations between hybrid and classical states. Single-molecule fluorescence resonance energy transfer was also used to observe aa-tRNA accommodation coupled with elongation factor G-mediated translocation. Dynamic rearrangements in tRNA configuration are also observed subsequent to the translocation reaction. This work underscores the importance of dynamics in ribosome function and demonstrates single-particle enzymology in a system of more than two components.

Acute encephalitis associated with measles: MRI features

We document the MRI features in six patients aged 5-14 years with acute encephalitis following measles. The diagnosis was made on a characteristic morbiliform rash and detection of specific IgM and IgG antibodies. The symptoms of encephalitis occurred 1-11 days after the appearance of the rash. All patients underwent MRI within 1-4 days of the onset of neurological symptoms. Diffusion weighted images (DWI) were obtained in three patients. In all patients, T2-weighted images showed widely distributed, multifocal high signal in both cerebral hemispheres with swelling of the cortex, with bilateral, symmetrical involvement of the putamen and caudate nucleus. The lesions had showed low apparent diffusion coefficients. Three patients showed subacute gyriform haemorrhage, and asymmetrical gyriform contrast enhancement on follow-up MRI.

Bone ingrowth on a smooth-surfaced hydroxyapatite-coated acetabular cup

We studied 29 retrieved smooth-surfaced hydroxyapatite (HA)-coated acetabular cups that had been in situ for an average of 54.9 months. The outer surface of all cups carried two circular grooves dividing the smooth surface. The extent of bony in-growth and hydroxyapatite absorption was calculated using a computer imaging system (analySIS-pro 3.0, Soft Imaging System GmbH, Germany). Absorption of HA was seen in all 29 cups. The extent of absorption was, on average, 60.5%. Twenty-five cups showed bony in-growth covering an average of 13.8% of the cup surface. Thirteen cups showed bony in-growth on the smooth surface as well as the circular grooves. On 11 cups, the bony in-growth was confined to the grooves. We found that bony in-growth on the smooth-surfaced HA-coated acetabular cup was minimal. It occurred along the two circular grooves rather than on the smooth surfaces. We conclude that a macro-structure surface enhancing bony in-growth is necessary for the long-term survival of the studied cup.

Mg2+-dependent conformational change of RNA studied by fluorescence correlation and FRET on immobilized single molecules

Fluorescence correlation spectroscopy (FCS) of fluorescence resonant energy transfer (FRET) on immobilized individual fluorophores was used to study the Mg2+-facilitated conformational change of an RNA three-helix junction, a structural element that initiates the folding of the 30S ribosomal subunit. Transitions of the RNA junction between open and folded conformations resulted in fluctuations in fluorescence by FRET. Fluorescence fluctuations occurring between two FRET states on the millisecond time scale were found to be dependent on Mg2+ and Na+ concentrations. Correlation functions of the fluctuations were used to determine transition rates between the two conformations as a function of Mg2+ or Na+ concentration. Both the opening and folding rates were found to vary with changing salt conditions. Assuming specific binding of divalent ions to RNA, the Mg2+ dependence of the observed rates cannot be explained by conformational change induced by Mg2+ binding/unbinding, but is consistent with a model in which the intrinsic conformational change of the RNA junction is altered by uptake of Mg2+ ion(s). This version of FCS/FRET on immobilized single molecules is demonstrated to be a powerful technique in the study of conformational dynamics of biomolecules over time scales ranging from microseconds to seconds.

Homodimers of mutant tryptophan synthase alpha-subunits in Escherichia coli

Tryptophan synthase alpha-subunit from Escherichia coli functionally exists as a heterotetramer of alpha(2)beta(2) with beta-subunit. While wild-type and mutant (F139W, T24M/F139W, and T24L/F139W) alpha-subunits were expressed as a monomer from recombinant plasmids in Escherichia coli, T24A/F139W, T24S/F139W, and T24K/F139W mutant alpha-subunits were abnormally expressed as soluble homodimers in addition to monomers. Monomers of dimer-forming mutant alpha-subunits retain high affinity to beta-subunit, high activity in stimulating catalytic activities of beta-subunit, and nearly intact content of secondary structure, indicating that the global structures of these monomers are identical to that of F139W alpha-subunit. However, fluorescence spectra of Trp139 and ANS binding indicate that significant perturbations occur in the mutant proteins. Interestingly, these defective properties of monomers caused by residue replacement were partially repaired by the dimer formation. As a result, it is suggested that dimers may be formed by domain or loop swapping, and that residue 24 may play important role in maintaining on-pathway of alpha-subunit folding.

Modulations of soleus H-reflex excitability during gait initiation: central versus peripheral influences

Soleus and tibialis anterior electromyogram (EMG) and soleus H-reflexes were recorded from the stance limb of an individual who suffered a traumatic peroneal nerve injury and of four nonimpaired individuals during gait initiation. The control subjects also initiated walking after swaying forward (sway-gait initiation), which eliminated the initial tibialis anterior activation. During the initial period of gait initiation, H-reflexes were depressed to 43% of standing values during normal-gait initiation and 86% during sway-gait initiation in the nonimpaired subjects. H-reflexes of the nerve-injured subject were depressed to 37%, even though no tibialis anterior EMG was observed. The findings support the view that reciprocal inhibition of the soleus during a task, which normally involves tibialis anterior activation, is due to a centrally mediated process.

Investigation of juxtasellar and cerebellopontine angle meningiomas and neurogenic tumours: two-phase helical CT

We performed two-phase helical CT in 31 patients with juxtasellar region and cerebellopontine angle tumours to evaluate its usefulness in differentiating meningiomas from neurogenic tumours. After the intravenous injection of 90 ml contrast medium at 3 ml/s, axial helical images were obtained with delays of 30 and 120 s. After the delayed axial images, we acquired coronal images. Changes in attenuation were assessed visually and quantitatively (by comparing the attenuation in Hounsfield units). There were 17 meningiomas and 14 neurogenic tumours, all pathologically proven. Two-phase helical CT showed a decrease in attenuation in 15 (88%) meningiomas and an increase in 14 (100%) neurogenic tumours from early to delayed axial images. Coronal images showed a decrease in attenuation in all 17 meningiomas and an increase in 13 (93%) of the neurogenic tumours. The mean HU and their ratios were significantly different between meningiomas and neurogenic tumours.

Tripartite structure of Saccharomyces cerevisiae Dna2 helicase/endonuclease

In order to gain insights into the structural basis of the multifunctional Dna2 enzyme involved in Okazaki fragment processing, we performed biochemical, biophysical and genetic studies to dissect the domain structure of Dna2. Proteolytic digestion of Dna2 using subtilisin produced a 127 kDa polypeptide that lacked the 45 kDa N-terminal region of Dna2. Further digestion generated two subtilisin-resistant core fragments of approximately equal size, 58 and 60 kDa. Surprisingly, digestion resulted in a significant (3- to 8-fold) increase in both ATPase and endonuclease activities compared to the intact enzyme. However, cells with a mutant DNA2 allele lacking the corresponding N-terminal region were severely impaired in growth, being unable to grow at 37 degrees C, indicating that the N-terminal region contains a domain critical for a cellular function(s) of Dna2. Analyses of the hydrodynamic properties of and in vivo complex formation by wild-type and/or mutant Dna2 lacking the N-terminal 45 kDa domain revealed that Dna2 is active as the monomer and thus the defect in the mutant Dna2 protein is not due to its inability to multimerize. In addition, we found that the N-terminal 45 kDa domain interacts physically with a central region located between the two catalytic domains. Our results suggest that the N-terminal 45 kDa domain of Dna2 plays a critical role in regulation of the enzymatic activities of Dna2 by serving as a site for intra- and intermolecular interactions essential for optimal function of Dna2 in Okazaki fragment processing. The possible mode of regulation of Dna2 is discussed based upon our recent finding that replication protein A interacts functionally and physically with Dna2 during Okazaki fragment processing.

Characterization of antidepressant-like effects of p-synephrine stereoisomers

We previously reported that p-synephrine has antidepressant-like activity in the murine models of forced swimming and tail suspension. In the present study, we characterized antidepressant-like effects of p-synephrine stereoisomers in both in vivo and in vitro systems. In the tail suspension test, S-(+)-p-synephrine (3 mg/kg, p.o.) reduced the duration of immobility, while R-(-)-p-synephrine (0.3-3 mg/kg, p.o.) had no effect. S-(+)-p-synephrine (0.3, 1 and 3 mg/kg, p.o.) and R-(-)-p-synephrine (1 mg/ kg and 3 mg/kg, p.o.) significantly reversed the reserpine (2.5 mg/kg, i.p.)-induced hypothermia. S-(+)-p-synephrine was more effective than R-(-)-p-synephrine in inhibition of both [3H]noradrenaline uptake in rat cerebral cortical slices (maximal inhibition 85.7 +/- 7.8% vs. 59.8 +/- 4.3%; EC50 5.8 +/- 0.7 microM vs. 13.5 +/- 1.2 microM) and [3H]nisoxetine binding (Ki 4.5 +/- 0.5 microM vs. 8.2 +/- 0.7 microM). In contrast, R-(-)-p-synephrine was more effective than S-(+)-p-synephrine in stimulation of [3H]noradrenaline release from rat cerebral cortical slices (maximal stimulation 23.9 +/- 1.8% vs. 20.1 +/- 1.7%; EC50 8.2 +/- 0.6 microM vs. EC50 12.3 +/- 0.9 microM). The stimulatory effect of R-(-)-p-synephrine on [3H]noradrenaline release was inhibited by nisoxetine (100 nM), but tetrodotoxin (1 microM) and elimination of extracellular calcium had no effect. It is suggested that S-(+)-p-synephrine has more effective antidepressant-like activity than R-(-)-p-synephrine.

Extracellular signal-regulated kinase/90-KDA ribosomal S6 kinase/nuclear factor-kappa B pathway mediates phorbol 12-myristate 13-acetate-induced megakaryocytic differentiation of K562 cells

Two signaling pathways, the extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase (MAPK)-dependent pathway and the nuclear factor-kappaB (NF-kappaB)-dependent pathway, have been known to mediate megakaryocytic differentiation of K562 cells induced by phorbol 12-myristate 13-acetate (PMA). In this study, we examined whether 90-kDa ribosomal S6 kinase (RSK), known as a substrate of ERK/MAPK and a signal-inducible IkappaBalpha kinase, would link two pathways during the differentiation. RSK1 was activated in a time- and dose-dependent manner during the PMA-induced differentiation. Overexpression of wild-type or dominant inhibitory mutant (D205N) of RSK1 enhanced or suppressed PMA-stimulated NF-kappaB activation and megakaryocytic differentiation as shown by morphology, nonspecific esterase activity, and expression of the CD41 megakaryocytic marker, respectively. In addition, overexpression of the dominant inhibitory mutant (S32A/S36A) of IkappaBalpha inhibited PMA-stimulated and RSK1-enhanced megakaryocytic differentiation, indicating that NF-kappaB mediates a signal for megakaryocytic differentiation downstream of RSK1. PMA-stimulated activation of ERK/MAPK, RSK1, and NF-kappaB and the PMA-induced megakaryocytic differentiation were prevented by pretreatment with PD98059, a specific inhibitor of the mitogen-activated ERK kinase (MEK). Therefore, these results demonstrate that the sequential ERK/RSK1/NF-kappaB pathway mediates PMA-stimulated megakaryocytic differentiation of K562 cells.

A co-operative study: clinical characteristics of 334 Korean patients with moyamoya disease treated at neurosurgical institutes (1976-1994). The Korean Society for Cerebrovascular Disease

A co-operative study was conducted to determine the clinical characteristics of patients with moyamoya disease who were diagnosed and treated at neurosurgical institutes in Korea before 1995. Twenty-six hospitals contributed 505 cases and among them, the clinical characteristics of 334 patients with definite moyamoya disease were evaluated. The number of patients began to increase from the late 1980s, and after that approximately 20 patients were treated each year. There were two age peaks: from six to 15 and from 31 to 40 years of age. Haemorrhagic manifestations occurred in approximately 43% of the patients. The major clinical manifestations were haemorrhage in adults (62.4%) and ischaemia in children (61.2%). Overall 54.5% of the patients experienced decreased consciousness levels, mainly due to intracranial haemorrhage or cerebral infarction. In the patients with ischemic manifestations, the adult patients were more likely to have cerebral infarction than the pediatric patients (80% vs. 39%) and the pediatric patients were more likely to have TIA (61% vs. 25%). Thirty eight percent of the patients underwent bypass surgery and 53% of these procedures were performed bilaterally. Treatment policies, including indications for bypass surgery and commonly used drugs, were somewhat different according to the institution. Overall favorable outcome was 73%, and the most significant factor affecting poor outcome was haemorrhagic manifestation. This article describes the characteristics of 334 patients with moyamoya disease, who were diagnosed and treated at neurosurgical institutes in Korea before 1995.

Novel nucleosides with vinyl fluoride or vinyl bromide moiety as open-chain analogs of neplanocin A

Novel nucleosides with vinyl fluoride and vinyl bromide were designed, synthesized and evaluated their antiviral activities against poliovirus, HSV, HIV, and HBV.

Lateralizing ability of single-voxel proton mr spectroscopy in hippocampal sclerosis: comparison with mr imaging and positron emission tomography

BACKGROUND AND PURPOSE

Proton MR spectroscopy (MRS) is still in the early stages in the evaluation of epilepsy, and comparisons with MR imaging and positron emission tomography (PET) in the same patients have rarely been documented. The purpose of this study was to evaluate the lateralizing ability of single-voxel MRS in comparison with MR imaging and PET in patients with hippocampal sclerosis.

METHODS

Thirty-three patients with intractable temporal lobe epilepsy whose MR imaging diagnosis was unilateral hippocampal sclerosis and who underwent anterior temporal lobectomy and had good postsurgical outcome over 1-year follow-up were included in the study. MR spectra were obtained from the hippocampus bilaterally, using the point-resolved spectroscopy sequence. Metabolite ratios of NAA/Cho and NAA/Cr were calculated from the relative peak height measurements. An NAA/Cho ratio of 0.8 or less and an NAA/Cr ratio of 1.0 or less were regarded as abnormal. The MRS results were compared retrospectively with those of MR imaging and PET as to the ability to lateralize the epileptogenic focus.

RESULTS

The sensitivity of MRS and PET (concordance with MR imaging) was 85% each in the lateralization of the ipsilateral lesion side. Bilateral abnormalities were seen in 30% of the patients. False-lateralization rates for MRS and PET were 3% and 6%, respectively. The concordance rate of MRS and PET was 73%, when comparing the results of the ipsilateral lesion side.

CONCLUSION

MRS may be used as an adjunct tool in the evaluation of hippocampal sclerosis, like PET, although its sensitivity has to be improved and the clinical significance of bilateral abnormality is still to be determined.

Structure-activity relationships of apio nucleosides as potential antiviral agents

Several types of novel apio nucleosides were synthesized starting from 1,3-dihydroxyacetone and evaluated for antiviral activity. Among compounds tested, amino substituted apio dideoxynucleosides exhibited anti-HBV activity, while thioapio dideoxynucleosides were found to be active against HIV-1. Apio dideoxydidehydro nucleosides showed moderate to potent anti-HCMV activity, but their bioisosteric thioapio dideoxydidehydro nucleosides did not exhibit any significant antiviral activity.

Synthesis of novel D- and L-3'-deoxy-3'-C-hydroxymethyl nucleoside with exocyclic methylene as potential ribonucleotide reductase inhibitor

D- and L-3'-Deoxy-3'-C-hydroxymethyl thymidine substituted with exocyclic methylene at 2'-position were synthesized, starting from D- and L-xylose as potential ribonucleotide reductase inhibitor, respectively, but they were found to be inactive against several tumor cell lines.

Synthesis of novel 3'-deoxy-3'-C-hydroxymethyl nucleosides with conformationally rigid sugar moiety as potential antiviral agents

Based on the fact that the ring expanded 3'-C-hydroxymethyl analogue of oxetanocin A exhibited potent antiviral activity, two types of conformationally rigid 3'-C-hydroxymethyl derivatives in which 2'-hydroxyl group is linked to the 4'-position or to the 6'-position were synthesized starting from 1,2;5,6-di-O-isopropylidene-D-glucose, respectively.

Design and synthesis of novel fluorocyclopropanoid nucleosides

Novel fluorocyclopropanoid nucleosides were designed, synthesized and evaluated their antiviral activities against poliovirus, HSV, HIV, and HBV.

Synthesis and antiviral activity of D- and L-2'-azido-2',3'-dideoxy-4'-thiopyrimidine and purine nucleosides

Novel D- and L-2'-azido-2',3'-dideoxy-4'-thionucleosides were synthesized starting from L- and D-xylose via D- and L-4-thioarabitol derivative as key intermediates and evaluated for antiviral activity, respectively. When the final nucleosides were tested against HIV-1, HSV-1, HSV-2, and HCMV, they were found to be only active against HCMV without cytotoxicity up to 100 micrograms/ml.