Dynamical localization and partial-barrier localization in the Paul trap

We investigate the nature of quantum localization exhibited by the center-of-mass motion of an ion in a Paul trap interacting with a standing laser field. Depending upon system parameters and the initial location of the ion, quantum suppression of chaotic diffusion is dominated by dynamical localization or localization due to partial barriers formed of broken separatrices and cantori.

Allozyme Variation and Genetic Relationships among Species of Cimicifuga (Ranunculaceae) from Korea

Allozyme investigation of the five Cimicifuga taxa in Korea was conducted to assess genetic and clonal diversity within populations and genetic divergence among populations and taxa. Levels of allozyme variation maintained in Korean Cimicifuga taxa were comparable to those for most herbaceous perennials. In general, samples excluding copies of the same multilocus genotype maintained higher levels of genetic diversity than the total samples within populations. Copies of homozygous genotypes at several loci resulting from clonal spread lead to decreased levels of genetic diversity within populations, indicating that clonal reproduction found in Cimicifuga affects population genetic structure. In general, more widely distributed species such as C. dahurica and C. japonica harbored higher levels of allozyme diversity than the other taxa examined. Although two varieties of C. heracleifolia are geographically and reproductively isolated, the genetic and clonal structure of var. bifida seems to resemble var. heracleifolia, indicating that the two varieties may have had a similar evolutionary history. However, the allozyme data strongly indicate that the two morphological types (Groups I and II) of C. simplex should be treated as separate species.

Measurement of ultralow supermirror birefringence by use of the polarimetric differential cavity ringdown technique

We demonstrate a novel technique for measuring ultralow linear birefringence of supermirrors (high-reflectivity dielectric mirror coatings). The polarimetric cavity ringdown technique is used in conjunction with the differential detection scheme with circular polarization to enhance the measurement sensitivity. The technique could, in principle, provide the convenience and reliability of linear detection signals and a reasonable tolerance to experimental imperfections. Phase retardation and orientation of each cavity mirror can be determined separately without the influence of the other mirror. The minimum detectable phase retardation achieved experimentally with this technique is ~6 x 10(-8) rad.

Protective role of nitric oxide-mediated inflammatory response against lipid peroxidation in ultraviolet B-irradiated skin

Ultraviolet (UV) irradiation is known to induce serious oxidative damage in the skin via lipid peroxidation. Nitric oxide (NO) synthesized by keratinocytes, melanocytes and endothelial cells in response to proinflammatory cytokines and UV radiation, has been reported to prevent UV-induced apoptosis in the skin. We have examined the effects of NO on UVB-induced lipid peroxidation in murine skin in vivo. UVB induced a dose-dependent increase in lipid peroxidation of skin extracts in vitro; however, lipid peroxidation in the skin in vivo remained unaffected at irradiation doses of less than 1.0 J cm-2 and decreased significantly at doses over 1.5 J cm-2 (P < 0.01). Time-delayed inhibition of lipid peroxidation in the skin in vivo was observed after irradiation at 1.5 J cm-2. Administration of N G-nitro-L-arginine methyl ester (L-NAME), an inhibitor of NO synthesis, enhanced lipid peroxidation (P < 0.05), while it suppressed the ear-swelling response (ESR), a biological marker of inflammation. By contrast, administration of sodium nitroprusside, an NO enhancer, suppressed lipid peroxidation (P < 0. 01), while it enhanced the ESR. Expression of inducible nitric oxide synthase (iNOS) was observed from 12 to 48 h postirradiation at doses of 0.4-1.6 J cm-2. The UVB-induced iNOS expression was markedly inhibited by L-NAME, suggesting that iNOS is a major enzyme in the production of NO. These results suggest that NO acts as a mediator of the inflammatory response in UVB-irradiated skin, and that lipid peroxidation is inversely regulated with the NO-mediated inflammatory response in vivo.

An endogenous proteinacious inhibitor in porcine liver for S-adenosyl-L-methionine dependent methylation reactions: identification as oligosaccharide-linked acyl carrier protein

A proteinacious inhibitor of S-adenosyl-L-methionine (AdoMet)-dependent transmethylation reactions was purified to homogeneity from porcine liver by size exclusion chromatography and FPLC. The molecular weight of the inhibitor was 12,222 Da. A 7400 Da polypeptide fragment of the purified inhibitor was sequenced by matrix-associated laser desorption ionization; time-of-flight MS, and was found to be identical with the known sequence of spinach acyl carrier protein (ACP). Although the remainder of the molecule was not clearly defined, 1H and H-H correlation of spectroscopy (COSY) NMR analysis revealed the presence of an oligosaccharide with alpha-glycosidic linkage. The purified oligosaccharide-linked ACP inhibited several AdoMet-dependent transmethylation reactions such as protein methylase I and II. S-farnesylcysteine O-methyltransferase, DNA methyltransferase and phospholipid methyltransferase. Protein methylase II was inhibited with a Ki value of 2.4 x 10(-3) M in a mixed inhibition pattern, whereas a well-known competitive product inhibitor S-adenosyl-L-homocysteine (AdoHcy) had Ki value of 6.3 x 10(-6) M. Commercially available active ACP fragments (65-74) and ACP from Escherichia coli had less inhibitory activity toward S-farnesylcysteine O-methyltransferase than the purified inhibitor. The biological significance of this oligosaccharide-linked ACP which has two seemingly unrelated functions (inhibitor for transmethylation and fatty acid biosynthesis) remains to be elucidated.

The new genotypic human calicivirus isolated in Seoul

A new type of human calicivirus (HuCV) showing the classic cup-shaped surface morphology was identified in the stool sample from a child with symptoms of acute gastroenteritis in Seoul, Korea (SK virus). Genomic RNA was extracted directly from the stool sample, and the nucleotide sequence of 3.2 kb of the 3' end of SK virus was determined from cDNA. This region spanned sequences from the RNA-dependent RNA polymerase (RDRP) region in the open reading frame 1 (ORF1) to the 3' poly A tail. The non-structural and capsid protein coding sequences were fused in a single ORF as observed in Manchester type (Genogroup III). However, ORF2 of Manchester virus was missing in SK virus. In RDRP region, SK virus showed amino acid and nucleotide identities of 74-75% and 68-69% respectively, with those of Manchester virus, while showed 34-46% and 55-60% identities respectively with those of other human caliciviruses. However, capsid protein of SK virus showed a partial (29-46%) amino acid identity with those of other caliciviruses including Manchester type. The closest resemblance in amino acid (97-99%) and nucleotide sequence (85-86%) identities were found in RDRP region with Vanderbijlpark and Pretoria isolates recently found in South Africa. These results suggest that SK virus together with Vanderbijlpark and Pretoria isolates belong to a new type different from Manchester virus.

Mapping of functional organization in human visual cortex: electrical cortical stimulation

OBJECTIVES

To investigate the pattern of functional organization in the human visual cortex through electrical cortical stimulation.

METHODS

Electrical cortical stimulation was applied to the occipital cortex and adjacent cortices using subdural grid electrodes in 23 epilepsy patients. Diverse visual responses were recorded. These responses were divided into different categories according to the specific response modalities, such as form, color, and motion. Form visual responses were further subdivided into simple, intermediate, and complex responses. The cortical localization of subdural electrodes was identified using MRI-CT coregistration. The cortical distribution of different visual responses was projected into three-dimensional surface renderings of the brain. The distribution and frequency of subdural electrodes showing different visual responses were quantified by calculating the percentage of the number of electrodes showing one specific type of visual response at the corresponding anatomic region to the total number of electrodes in all brain regions that produced the same response.

RESULTS

Simple form responses were obtained mostly at the occipital pole and the inferior occipital gyrus (47.4%) and the striate cortex (42.4%). Intermediate form responses occurred mainly on the peristriate cortex (52.5%) and the lateral occipital (28.0%) and fusiform gyri (19.5%). Complex forms were produced by stimulation of the basal temporo-occipital region (57.6%) and the lateral temporal or lateral temporo-occipital junctional region (42.4%). Color responses occurred on the basal occipital area, mostly at the fusiform (40.0%) and lingual gyri (36.0%). Moving sensations were evoked by stimulation of the basal temporo-occipital (28.4%) and the mesial parieto-occipital or temporo-parieto-occipital junctional regions (23.9%).

CONCLUSIONS

Different modalities of vision, such as form, color, and moving sensation, appeared to be distributed and organized in different areas of the human visual cortex.

Broad Halpha Wing Formation in the Planetary Nebula IC 4997

The young and compact planetary nebula IC 4997 is known to exhibit very broad wings with a width exceeding 5000 km s-1 around Halpha. We propose that the broad wings are formed through Rayleigh-Raman scattering that involves atomic hydrogen, by which Lybeta photons with a velocity width of a few 102 km s-1 are converted to optical photons and fill the Halpha broad wing region. The conversion efficiency reaches 0.6 near the line center, where the scattering optical depth is much larger than 1, and rapidly decreases in the far wings. Assuming that close to the central star there exists an unresolved inner compact core of high density, nH approximately 109-1010 cm-3, we use the photoionization code "CLOUDY" to show that sufficient Lybeta photons for scattering are produced. Using a top-hat-incident profile for the Lybeta flux and a scattering region with a H i column density NHi=2x1020 cm-2 and a substantial covering factor, we perform a profile-fitting analysis in order to obtain a satisfactory fit to the observed flux. We briefly discuss the astrophysical implications of the Rayleigh-Raman processes in planetary nebulae and other emission objects.

Aromatase and sulfatase inhibitors from Lepiota americana

From an edible mushroom Lepiota americana Pk., (Agaricaceae), 2-aminophenoxazin-3-one that inhibited aromatase at IC50 = 5.7 microM and 3 beta-hydroxy-5,8-epidioxyergosta-6,22-diene that inhibited sulfatase at IC50 = 0.9 microM were isolated. Neither 2-aminophenoxazin-3-one was active against sulfatase nor was 3 beta-hydroxy-5,8-epidioxyergosta-6,22-diene active against aromatase.

Essential role for Max in early embryonic growth and development

Loss of Max function in the mouse resulted in generalized developmental arrest of both embryonic and extraembryonic tissues at early postimplantation (approximately E5.5-6.5), coincident with loss or dilution of maternal Max stores in the expanding embryo in vivo and in blastocyst outgrowths in vitro. Developmentally arrested embryos were reduced in size and exhibited widespread cytological degeneration and feeble BrdU incorporation. Max and, by extension, the Myc superfamily, serve essential roles in early mammalian development and a maternal reservoir of Max exists in sufficient amount to sustain Myc superfamily function through preimplantation stages of development.

Novel biphasic effect of pyrrolidine dithiocarbamate on neuronal cell viability is mediated by the differential regulation of intracellular zinc and copper ion levels, NF-kappaB, and MAP kinases

Nuclear factor kappaB (NF-kappaB) is a transcription factor involved in the expression of a wide range of genes, most of which code for proteins that play a role in immunity and inflammation. Pyrrolidine dithiocarbamate (PDTC) is a well-known inhibitor of NF-kappaB. Although its mechanism of action is conferred by its antioxidant property, other mechanisms by which PDTC can act as a prooxidant, metal chelator, and free thiol group modulator have recently been suggested. Here we report that PDTC caused a dual effect on cell viability in neuronal rat pheochromocytoma (PC12) cells, depending on its concentration. Increase of intracellular zinc and copper ion levels selectively potentiated the cytotoxic PDTC effect in a dose-dependent manner, and thiol reagents, such as glutathione and N-acetylcysteine, as well as divalent metal-chelating reagents, such as EDTA and bathocuproline disulfonic acid, blocked its cell death effect. The differential effect of PDTC on cell viability correlates well with the inhibition of NF-kappaB activities. In addition, PDTC differentially activated microtubule-associated protein (MAP) kinases, such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), but not p38, depending on its dose, and the coaddition of glutathione (GSH), other antioxidants, and metal ions also modulated their activities. Furthermore, stable Bcl-2 expression blocked the PDTC-induced cell death. These results suggest that the thiol groups and free zinc and copper ion levels are important for the novel biphasic PDTC effect on cell viability, which is associated with the differential activation of NF-kappaB and MAP kinases.

Partial seizures manifesting as apnea only in an adult

PURPOSE

Although several cases of apneic seizures have been reported in neonates, epileptic seizures presenting as apnea only in adults are very rare. We present a case report of a 19-year-old man with viral encephalitis and frequent episodes of apneic seizures.

METHODS

Prolonged electroencephalograms (EEGs), respiratory monitorings, and imaging including ictal-interictal subtraction single photon emission computed tomography (SPECT) coregistered with magnetic resonance imaging (MRI) were performed.

RESULTS

Ictal EEGs recorded during apneic episodes showed repetitive sharp waves or rhythmic theta activity arising from the left or right independent bitemporal region. Ictal SPECT was performed during one episode of apnea that showed ictal EEG discharges arising from the left posterior temporal area. Ictal-interictal subtraction SPECT coregistered with MRI revealed that the seizures originated from the left, posterior, midlateral temporal cortex.

CONCLUSIONS

Previous studies with ictal EEG or brain stimulation suggest that apneic seizures might be mediated through the limbic and associated cortical systems. Our study reports on a very rare case of partial seizures with apnea only in an adult patient and is supported by ictal EEG and ictal-interictal subtraction SPECT coregistered with MRI.

Exactly solvable two-way traffic model with ordered sequential update

Within the formalism of the matrix product ansatz, we study a two-species asymmetric exclusion process with backward and forward site-ordered sequential updates. This model, which was originally introduced with the random sequential update [J. Phys. A 30, 8497 (1997)], describes a two-way traffic flow with a dynamic impurity and shows a phase transition between the free flow and the traffic jam. We investigate characteristics of this jamming and examine similarities and differences between our results and those with a random sequential update.

Comparison of rocuronium and vecuronium pretreatment for prevention of fasciculations, myalgia and biochemical changes following succinylcholine administration

BACKGROUND

The purpose of this study was to assess the effect of rocuronium pretreatment on the succinylcholine-induced fasciculations, myalgia and biochemical changes, and to compare it with vecuronium pretreatment.

METHODS

We have studied 60 female patients undergoing minor elective surgery, in a prospective double blinded method. Three groups of 20 patients each was pretreated with either saline (control group), rocuronium 0.05 mg/kg (rocuronium group) or vecuronium 0.007 mg/kg (vecuronium group). Three min after the pretreatment, 1.5 mg/kg succinylcholine was injected. Single twitch responses to electrical stimulation were measured. Serum potassium and creatine kinase were respectively measured 5 min after succinylcholine and 24 h after operation. Fasciculations and myalgia on postoperative day 1 and day 2 were evaluated.

RESULTS

The incidence of fasciculations was lowest in the rocuronium group, followed by the vecuronium group, and was highest in the control group. The incidence of myalgia on postoperative day 1 was lower in the rocuronium and vecuronium groups than the control group. The increase of serum creatine kinase was similar among the three groups, but there was no increase in serum potassium concentration in any group. No differences of the single twitch responses to electrical stimulation were found between the rocuronium and vecuronium groups.

CONCLUSIONS

Rocuronium pretreatment was more effective in reducing fasciculations than was vecuronium pretreatment, but both were equally effective in preventing myalgia on postoperative day 1. This difference may reflect the differential activities of rocuronium and vecuronium at the neuromuscular junction. The increase of creatine kinase was not attenuated by any regimen.

The time course of phonological, semantic, and orthographic coding in reading: evidence from the fast-priming technique

The present experiment employed the fast-priming paradigm in reading (Sereno & Rayner, 1992), in which sentences are silently read while eye-movement-contingent changes are made on a specified target region. In this paradigm, when readers fixate on a specified target word region, a prime word is encountered for a brief duration at the beginning of the fixation and then it is replaced by a target word. Three types of primes were employed: homophones, semantically related, and orthographically similar, and five prime durations were employed: 29, 32, 35, 38, and 41 msec. The primary finding was that significant homophone priming was obtained at prime durations ranging from 29 to 35 msec, whereas significant semantic priming occurred only at the 32-msec prime duration. In contrast, significant orthographic priming occurred at all prime durations. These findings indicate that phonological codes are activated during an eye fixation at least as rapidly as semantic codes. An explanation for the pattern of events is suggested using the framework of an activation-verification model.

Differential expression of nitric oxide synthase in human stomach cancer

The level of expression and cellular localization of isoenzymes of nitric oxide synthase (NOS) was detected in human stomach tumor tissues. Tumor tissues showed 70% higher activity of NOS than that of normal tissues (P < 0.01). Poorly differentiated adenocarcinoma tend to have higher activity (P < 0.05) than well differentiated and moderately differentiated tumor tissues. Aminoguanidine (AG), 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT), NG-monomethyl-L-arginine (L-NMMA), and Nomega-nitro-L-arginine (L-NNA) inhibited NOS activity in tumor tissues by 18, 14, 11 and 13%, respectively. The TNF-alpha mRNA expression was correlated with the inducible NOS (iNOS) level, which was high in adenocarcinomas and low in normal tissues. Tumor tissues showed higher expression of iNOS in gland epithelial cells but the level of eNOS was significantly decreased with an exception of concentrated localization in the proliferating capillary endothelium. These results revealed that isoforms of NOS might contribute differentially to growth and progression of human stomach tumor.

Hydrogen peroxide activates p70(S6k) signaling pathway

We investigated a possible role of reactive oxygen species (ROS) in p70(S6k) activation, which plays an important role in the progression of cells from G(0)/G(1) to S phase of the cell cycle by translational up-regulation of a family of mRNA transcripts that encode for components of the protein synthetic machinery. Treatment of mouse epidermal cell JB6 with H(2)O(2) generated extracellularly by glucose/glucose oxidase led to the activation of p70(S6k) and p90(Rsk) and to phosphorylation of p42(MAPK)/p44(MAPK). The activation of p70(S6k) and p90(Rsk) was dose-dependent and transient, maximal activities being in extracts treated for 15 and 30 min, respectively. Further characterization of ROS-induced activation of p70(S6k) using specific inhibitors for p70(S6k) signaling pathway, rapamycin, and wortmannin revealed that ROS acted upstream of the rapamycin-sensitive component FRAP/RAFT and wortmannin-sensitive component phosphatidylinositol 3-kinase, because both inhibitors caused the inhibition of ROS-induced p70(S6k) activity. In addition, Ca(2+) chelation also inhibited ROS-induced activation of p70(S6k), indicating that Ca(2+) is a mediator of p70(S6k) activation by ROS. However, down-regulation of 12-O-tetradecanoylphorbol-13-acetate (TPA)-responsive protein kinase C (PKC) by chronic pretreatment with TPA or a specific PKC inhibitor Ro-31-8220 did not block the activation of p70(S6k) by ROS, indicating that the activation of TPA-responsive PKC was not required for stimulation of p70(S6k) activity by H(2)O(2) in JB6 cells. Exposure of JB6 cells to platelet-derived growth factor or epidermal growth factor led to a rapid increase in H(2)O(2), phosphorylation, and activation of p70(S6k), which were antagonized by the pretreatment of catalase. Taken together, the results suggest that ROS act as a messenger in growth factor-induced p70(S6k) signaling pathway.

Electrophysiological evidence for the role of substance P in retinohypothalamic transmission in the rat

The retinohypothalamic tract (RHT) is a neural pathway through which photic time cues are delivered directly to the mammalian circadian pacemaker in the suprachiasmatic nucleus (SCN). Although the excitatory amino acid glutamate is the primary neurotransmitter in the RHT, other substances such as substance P (SPq also have been suggested to play a role. The present study tested the hypothesis that SP participates in retinohypothalamic transmission and selectively modulates either N-methyl-D-aspartate (NMDA) or non-NMDA receptor-mediated neurotransmission. The SP antagonist L-703,606 depressed the excitatory postsynaptic current (EPSC) evoked by optic nerve stimulation in SCN neurons in rat hypothalamic slices. The SP antagonist also had a similar depressive effect on the NMDA and non-NMDA receptor-mediated components of the EPSC. These results suggest that SP is an excitatory neuromodulator contributing to the expression of both the NMDA and non-NMDA receptor-mediated components of retinohypothalamic transmission.

Chaos and reconnection in relativistic cyclotron motion in an elliptically polarized electric field

A theoretical study of the relativistic cyclotron motion occurring in a uniform magnetic field and an oscillating electric field of arbitrary polarization is performed, which aims at determining the effect of the ellipticity and the strength of the electric field upon the integrability or nonintegrability of the system. Unless a circularly polarized electric field is used, the cyclotron system is nonintegrable and displays stochastic behavior in the region where resonance islands overlap. It is found, however, that the stochastic layers become increasingly thin as the polarization angle is moved closer toward pi/2 (circular polarization). If the polarization angle is held fixed and the electric field amplitude is increased, the Kolmogorov-Arnold-Moser curves separating the resonance islands experience a reconnection process through which the islands are topologically rearranged. When the rearrangement is accomplished, the phase space is occupied mostly by regular trajectories.

Pituitary adenylate cyclase-activating polypeptide regulation of vasoactive intestinal polypeptide transcription requires Ca2+ influx and activation of the serine/threonine phosphatase calcineurin

A >15-fold increase in vasoactive intestinal polypeptide (VIP) mRNA and VIP peptide levels occurred in primary chromaffin cells following exposure to the neurotrophic neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP)-27 with an EC50 of approximately 2 nM. PACAP induction of VIP expression was blocked by methoxyverapamil or by a combination of nimodipine and omega-conotoxin MVIIC, indicating a requirement for PACAP-initiated calcium entry through voltage-dependent calcium channels for regulation of VIP biosynthesis. Ascomycin, which inhibits calcineurin through formation of an ascomycin/FKBP12/calcineurin ternary complex, abolished the PACAP-evoked increase in VIP expression, whereas rapamycin, which also binds to FKBP12 but does not cause inhibition of calcineurin, did not. Cyclosporin A, which inhibits calcineurin through formation of a cyclosporin A/cyclophilin/calcineurin complex, also abolished PACAP-evoked VIP biosynthesis. These data indicate that PACAP regulates the expression of VIP via a signaling pathway that requires calcium influx and activation of calcineurin.

Evaluation of the malaria threat at the multipurpose range complex, Yongp'yong, Republic of Korea

As part of an operational effort to control the transmission of malaria after its reemergence in the Republic of Korea, a number of U.S. military and Korean civilian health workers assessed the situation at a large training site where two cases had been transmitted. The vector mosquitoes (Anopheles sinensis) probably had a limited flight range (< 1 km) in this situation based on low numbers in permanent light traps and biting collections at the billeting area compared with collections from light traps and larval surveys where the mosquito was abundant. The threat of malaria was proven by the presence of infected local Korean residents (13 of 105 sampled). However, only a small proportion of U.S. soldiers (39 of 78 surveyed) at the training site used personal protective measures. Further efforts should include improved techniques for informing and motivating soldiers to use personal protective measures and cooperation with Korean authorities to perform vector control in civilian areas bordering the training area.

Identification of highly methylated arginine residues in an endogenous 20-kDa polypeptide in cancer cells

Enzymatic methylation of endogenous proteins in several cancer cell lines was investigated to understand a possible relationship between protein-arginine methylation and cellular proliferation. Cytosolic extracts prepared from several cancer cells (HeLa, HCT-48, A549, and HepG2) and incubated with S-adenosyl-L-[methyl-3H]methionine revealed an intensely [methyl-3H]-labeled 20-kDa polypeptide. On the other hand, cytosolic extracts prepared from normal colon cells did not show any methylation of the 20-kDa protein under identical conditions. To identify nature of the 20-kDa polypeptide, purified histones were methylated with HCT-48 cytosolic extracts and analyzed by SDS-PAGE. However, none of the histones comigrated with the methylated 20-kDa polypeptide, indicating that it is unlikely to be any of the histone subclasses. The [methyl-3H]group in the 20-kDa polypeptide was stable at pH 10-11 (37 degrees C for 30 min) and methylation was not stimulated by GTPgammaS (4 mM), thus the reaction is neither carboxyl methylesterification on isoaspartyl residues, nor on C-terminal farnesylated cysteine. The present study together with the previous identification of N(G)-methylated arginine residues in the HCT-48 cytosol fraction suggests that this novel endogenous 20-kDa arginine-methylation is a cellular proliferation-related posttranslational modification reaction.

Inducible nitric oxide synthase inhibitors from Melia azedarach var. japonica

In bioassay-guided search for inducible nitric oxide synthase (iNOS) inhibitory compounds from higher plants of South Korea, two beta-carboline alkaloids, 4-methoxy-1-vinyl-beta-carboline (1) and 4,8-dimethoxy-l-vinyl-beta-carboline (2) have been isolated from the cortex of Melia azedarach var. japonica. The structures of these compounds were elucidated on the basis of spectroscopic data. Compounds 1 and 2 showed marked inhibitory activity of iNOS on LPS- and interferon-gamma-stimulated RAW 264.7 cells.

Unidirectional single-mode Nd:YAG laser with a planar semimonolithic ring cavity

Unidirectional single-mode operation of a diode-pumped Nd:YAG laser with a planar semimonolithic ring cavity has been demonstrated at 1064 nm. The semimonolithic cavity consists of a laser active medium placed in a magnetic field, a crystal quartz plate, and an output coupling mirror, which form an optical diode by acting as a Faraday rotator, a reciprocal polarization rotator, and a partial polarizer, respectively. A single-mode output power of 155 mW and a slope efficiency of 17% were obtained with a 1.2-W diode laser at 809 nm. A laser linewidth of less than 100 kHz is inferred from a beat note frequency spectrum between two identical laser systems and continuous tuning to greater than 2 GHz was observed.

In situ localization of p53, bcl-2 and bax mRNAs in rat ocular tissue

We mapped p53, bcl-2 and bax mRNAs, which are known to have correlation with apoptotic cell death, in the rat ocular tissue. p53 mRNA signals were present in several layers of retina, optic nerve, corneal epithelium, ciliary process and posterior surface of the iris. While almost the same pattern as p53 was recognized in the case of bcl-2 mRNA, bax signals were not found in ocular tissue except for ganglion cell layer (GCL). These results suggest that in the normal ocular tissue, p53 and bcl-2 genes play opposing parts in the physiological control of cell survival and death. A p53 mediated tumor-suppressing action might occur through the induction of transcriptional targets other than bax because only in GCL were p53 and bax mRNA expression co-localized.

Both inducible and constitutive activator protein-1-like transcription factors are used for transcriptional activation of the galanin gene by different first and second messenger pathways

We investigated trans-acting factors mediating galanin (GAL) gene activation by protein kinase-dependent signal transduction pathways in chromaffin cells. GAL mRNA up-regulation via the protein kinase A (PKA) pathway (25 microM forskolin) required new protein synthesis. Stimulation via protein kinase C (0.1 microM phorbol myristate acetate) did not. The involvement of activator protein-1(AP-1) and cAMP response element-binding protein (CREB) in serine/threonine protein kinase activation of GAL gene transcription was assessed. Cotransfection of a GAL reporter gene along with expression plasmids encoding c-Jun plus c-Fos, or the catalytic subunit of PKA (PKAbeta), resulted in a 4- to 8-fold enhancement of GAL reporter gene transcription. Transcriptional activation required the galanin 12-O-tetradecanoylphorbol-13-acetate (phorbol-12-myristate-13-acetate) response element (GTRE) octamer sequence (TGACGCGG) in the proximal enhancer of the GAL gene, previously shown to confer phorbol ester responsiveness in chromaffin cells. CREB coexpression did not stimulate GAL gene transcription or increase transcriptional activation by PKAbeta. The GTRE preferentially bound in vitro synthesized Jun and Fos-Jun, compared with CREB, in electrophoretic mobility shift assays. The GTRE preference for binding AP-1-immunoreactive protein compared with CREB was even more pronounced in chromaffin cell nuclear extracts, in which the majority of GTRE-bound protein in electrophoretic mobility shift assays was supershifted with anti-Fos and anti-Jun antibodies. Thus, GAL gene regulation mediated by protein kinase activation appears to involve both constitutively expressed and inducible AP-1-related proteins. Elevated potassium stimulation of GAL mRNA was completely blocked, but pituitary adenylyl cyclase-activating polypeptide and histamine stimulations were only partially blocked, by cycloheximide. Both inducible and constitutive pathways are therefore used by physiologically relevant first messengers that stimulate GAL biosynthesis in vivo.

Identification of the genes encoding enzymes involved in the early biosynthetic pathway of pteridines in Synechocystis sp. PCC 6803

The biosynthetic pathway for the pteridine moiety of cyanopterine, as well as tetrahydrobiopterine, has been investigated in Synechocystis sp. PCC 6803. Open reading frames slr0426, slr1626, slr0078 and sll0330 of the organism putatively encoding GTP cyclohydrolase I, dihydroneopterine aldolase, 6-pyruvoyltetrahydropterine synthase and sepiapterine reductase, respectively, have been cloned into T7-based vectors for expression in Escherichia coli. The recombinant proteins have been purified to homogeneity and demonstrated to possess expected genuine activities except that of sll0330. Our result is the first direct evidence for the functional assignment of the open reading frames in Synechocystis sp. PCC 6803. Furthermore, the 6-pyruvoyltetrahydropterine synthase gene is demonstrated for the first time in prokaryotes. Based on the result, biosynthesis of cyanopterine is discussed.

An endogenous proteinacious inhibitor for S-adenosyl-L-methionine-dependent transmethylation reactions; identification of S-adenosylhomocystein as an integral part

A proteinacious inhibitor with a molecular weight of 1,600 Da which inhibits S-adenosyl-L-methionine-dependent transmethylation reactions was purified from porcine liver to homogeneity by procedures including boiling, Sephadex G-25 column chromatography and repeated HPLC. Employing both Nuclear Magnetic Resonance (NMR) and Fast Atom Bombardment-Mass (FAB-Mass) spectroscopy, S-adenosylhomocysteine was conclusively identified as an integral part of the inhibitor. The purified S-adenosylhomocysteine was competitive with S-adenosyl-L-methionine with Ki value of 6.3x10(-6) M towards protein methylase II.

Disease states associated with telomerase deficiency appear earlier in mice with short telomeres

Mice deficient for the mouse telomerase RNA (mTR-/-) and lacking telomerase activity can only be bred for approximately six generations due to decreased male and female fertility and to an increased embryonic lethality associated with a neural tube closure defect. Although late generation mTR-/- mice show defects in the hematopoietic system, they are viable to adulthood, only showing a decrease in viability in old age. To assess the contribution of genetic background to the effect of telomerase deficiency on viability, we generated mTR-/- mutants on a C57BL6 background, which showed shorter telomeres than the original mixed genetic background C57BL6/129Sv. Interestingly, these mice could be bred for only four generations and the survival of late generation mTR-/- mice decreased dramatically with age as compared with their wild-type counterparts. Fifty percent of the generation 4 mice die at only 5 months of age. This decreased viability with age in the late generation mice is coincident with telomere shortening, sterility, splenic atrophy, reduced proliferative capacity of B and T cells, abnormal hematology and atrophy of the small intestine. These results indicate that telomere shortening in mTR-/- mice leads to progressive loss of organismal viability.

The effects of peripheral leukocytes on the hippocampal neuronal changes in transient global ischemia and unilateral cerebral hemispheric infarction

The participation of activated leukocytes and subsequent production of chemical mediators has been well accepted in the pathophysiology of hypoxic-ischemic injury. This study was performed to see the effects of leukocytes on hippocampal neuronal damage in transient global ischemia induced by 10-min occlusion of bilateral common carotid arteries (CCAs) with reperfusion for various times, and in complete unilateral ischemia induced by 24-hr ligation of left CCA. Leukopenia was induced by intraperitoneal injection of cyclophosphamide for 4 days. The results showed that hippocampal neuronal damages were worse at 6-hr reperfusion in leukopenic experimental group than in the control group. In comparison, 24-hr and 3-day reperfusion leukopenic groups showed less numbers of damaged neurons and milder changes. The 5-day reperfusion group showed inconsistent changes. Unilateral CCA occlusion showed extensive infarction in 83.3% of gerbils in the control group, compared to 25% of gerbils in the experimental group (p<0.05). These results strongly suggest that the number of peripheral leukocytes were closely related to the development of delayed neuronal damage of hippocampus in transient global ischemia and the incidence of infarction induced by 24-hr unilateral CCA ligation.

Border malaria characters of reemerging vivax malaria in the Republic of Korea

Since 1993, the number of vivax malaria cases has increased every year in the northern part of the Republic of Korea (ROK). This study was designed to characterize factors related to the reemergence of malaria in the ROK. A total of 21 cases diagnosed in 1993 and 1994 distributed sporadically in the narrow zone along the demilitarized zone (DMZ). Of total 317 civilian inhabitant cases reported in 1994-1997, 287 cases were studied and 80.8% of them resided within 10 km from the southern border of the DMZ. The frequency distribution of anti-Plasmodium vivax antibody titers using indirect fluorescent antibody test was compared in three villages in relation with distance from the DMZ. The number of inhabitants with high antibody titers was larger in the village nearest to the border than that in more distant villages. The present results highly suggested that the reemerging vivax malaria start in the border area, most possibly caused by infected mosquitoes which flew across the border. This pattern of transmission repeated year after year.

Quantum-classical correspondence in localization of eigenstates for a system having mixed-type classical dynamics

We have examined the localization properties of quantum eigenstates for a system having mixed-type classical dynamics. Emphasis is given to the structure of eigenfunctions and the local spectral density of states. The nature of strongly localized eigenstates can be explained by considering the corresponding classical motion on the Kolmogorov-Arnold-Moser tori. The weak localization of nearly delocalized eigenstates is not a quantum effect as is dynamical localization but a consequence of classical dynamics.

Dynamic states of a continuum traffic equation with on-ramp

We study the phase diagram of the continuum traffic flow model of a highway with an on-ramp. Using an open boundary condition, traffic states and metastabilities are investigated numerically for several representative values of the upstream boundary flux f(up) and for the whole range of the on-ramp flux f(rmp). An inhomogeneous but time-independent traffic state (standing localized cluster state) is found and related to a recently measured traffic state. Due to the density gradient near the on-ramp, a traffic jam can occur even when the downstream density is below the critical density of the usual traffic jam formation in homogeneous highways, and its structure varies qualitatively with f(rmp). The free flow, the recurring hump (RH) state, and the traffic jam can all coexist in a certain metastable region where the free flow can undergo phase transitions either to the RH state or to the traffic jam state. We also find two nontrivial analytic solutions. These solutions correspond to the standing localized cluster state and the homogeneous congested traffic state (one form of the traffic jam), which are observed in numerical simulations.

Effects of ethanol and its metabolite acetaldehyde on responses of the rat bladder

OBJECTIVE

To investigate the pharmacological effects of ethanol and its metabolite acetaldehyde on isolated rat bladder muscle, and thus assess the potential influence of ethanol ingestion on the risk of urinary retention in patients with benign prostatic hyperplasia.

MATERIALS AND METHODS

Isometric tension changes of isolated rat bladder muscle strips were recorded in an organ bath using a pressure transducer. The acute or prolonged effects of ethanol (1-4%) or acetaldehyde (0.01, 0.1 or 1 mmol/L) were assessed on resting tension, electrical field stimulation (EFS), and bethanechol- (0.5 mmol/L), ATP- (2 mmol/L) or KCl- (127 mmol/L) induced contraction. To determine the mechanism of acetaldehyde-induced stimulation, an antihistamine, diphenhydramine was used after bethanechol stimulation.

RESULTS

At the concentrations used, ethanol and acetaldehyde did not change the pH of the bathing medium. The resting tension of the muscle was not changed by ethanol, and acetaldehyde caused only a small increase in baseline tone at 1 mmol/L. Incubation with ethanol or acetaldehyde significantly suppressed contractility induced by EFS, bethanechol, ATP or KCl at each concentration (P<0.05). Contractions induced by all drugs were not changed significantly by the acute application of ethanol and the acute application of acetaldehyde did not affect contractions induced by ATP or KCl. However, EFS- or bethanechol-induced contractions were significantly enhanced (P<0. 05). The acetaldehyde-induced effects were completely blocked by the H1 antagonist, diphenhydramine (10 micromol/L).

CONCLUSIONS

Ethanol did not affect resting tension but acetaldehyde and ethanol suppressed bladder muscle contractions. However, direct acetaldehyde-stimulation may release histamine and enhance contractility. This suggests that chronic alcoholism rather than acute intoxication is more likely to provoke urinary retention.

Mutation of p53 and K-ras, and loss of heterozygosity of APC in intrahepatic cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is the second most common malignant tumor in liver; however, the carcinogenic mechanism of ICC is poorly understood. To analyze the molecular carcinogenesis of ICC, we examined the alterations of the p53, APC, and K-ras genes in 40 surgically resected ICC cases. The single-strand conformation polymorphism/sequencing revealed a p53 mutation in 12 cases (30%). An immunohistochemical overexpression of the p53 gene was detected in 10 cases (25%). The PCR/RFLP showed loss of heterozygosity of APC in 4 of 17 informative cases (23.5%). And the PCR/RFLP assay of K-ras codon 12 revealed the mutation in nine cases (22.5%). Twenty-one cases (52.5%) showed an alteration of at least one of the examined genes, and six (15%) carried an abnormality in more than two genes. The analysis of the clinicopathologic findings disclosed a significant relationship between the genetic alteration and gross type of the tumor: the p53 mutation was prominent in the ICC of mass-forming type, and K-ras mutation occurred more frequently in the ICC of periductal extension type (p < 0.05). These data suggest that each of the examined genes is involved in the development of ICC and that the p53 and K-ras mutation may play a role in the tumor growth pattern.

Measurement of the linewidth of a continuous-wave laser with a cavity-length modulation technique

We introduce a Fabry-Perot cavity-length modulation technique for measuring the linewidth of a continuous wave (cw) laser. We calculate the peak intensity of a cw laser transmitted through a Fabry-Perot cavity as a function of mirror speed. By fitting the experimental data to the results of the calculation, we determine the linewidth of a frequency-stabilized cw laser. The linewidth of a cw ring dye laser measured in the 570-590-nm wavelength range is approximately 170 +/- 20 kHz. We also demonstrate the use of this technique to measure the reflectivity of a high-reflectance mirror.

Cavity ringdown spectroscopy with a continuous-wave laser: calculation of coupling efficiency and a new spectrometer design

For the efficient operation of a cavity ringdown spectroscopy (CRDS) system utilized with a continuous-wave (cw) laser, we numerically analyze the coupling efficiency of a cw laser to a ringdown cavity in terms of changes in the scanning rate, the laser linewidth, and the mirror reflectivity. We also demonstrate a new simple design for a CRDS system that can produce a CRDS signal with only a piezoelectric transducer (PZT), without the acousto-optic modulator that is usually adopted to switch off the cw laser beam that enters the cavity. Furthermore, we investigate the feasibility of the cw CRDS technique with a fast-scanning PZT by recording a CRDS spectrum of acetylene overtones. The detection sensitivity that corresponds to the noise-equivalent absorption is found to be approximately 3 x 10(-9)/cm.

Longevity, stress response, and cancer in aging telomerase-deficient mice

Telomere maintenance is thought to play a role in signaling cellular senescence; however, a link with organismal aging processes has not been established. The telomerase null mouse provides an opportunity to understand the effects associated with critical telomere shortening at the organismal level. We studied a variety of physiological processes in an aging cohort of mTR-/- mice. Loss of telomere function did not elicit a full spectrum of classical pathophysiological symptoms of aging. However, age-dependent telomere shortening and accompanying genetic instability were associated with shortened life span as well as a reduced capacity to respond to stresses such as wound healing and hematopoietic ablation. In addition, we found an increased incidence of spontaneous malignancies. These findings demonstrate a critical role for telomere length in the overall fitness, reserve, and well being of the aging organism.

Inhibition of lipopolysaccharide-induced inducible nitric oxide (iNOS) mRNA expression and nitric oxide production by higenamine in murine peritoneal macrophages

Nitric oxide synthesized by inducible nitric oxide synthase (iNOS) has been implicated as a mediator of inflammation in rheumatic and autoimmune diseases. The effects of higenamine, a tetrahydroisoquinoline compound, on induction of NOS by bacterial lipopolysaccharide (LPS) were examined in murine peritoneal macrophages. LPS-induced nitrite/nitrate production was markedly inhibited by higenamine which at 0.01 mM, decreased nitrite/nitrate levels by 48.7+/-4.4%. This was comparable to the inhibition of LPS-induced nitrite/nitrate production by tetrandrin (49.51+/-2.02%) at the same concentration. Northern and Western blot analysis of iNOS expression demonstrated that iNOS expression was significantly attenuated following co-incubation of peritoneal macrophages with LPS (10 microg/ml; 18 hrs) and higenamine (0.001, 0.01 mM; 18 hrs). These results suggest that higenamine can inhibit LPS-induced expression of iNOS mRNA in murine peritoneal macrophages. The clinical implications of these findings remain to be established.

Characterization of a novel unconjugated pteridine glycoside, cyanopterin, in Synechocystis sp. PCC 6803

A new pteridine glycoside, called cyanopterin, was isolated from Synechocystis sp. PCC 6803 and its structure was elucidated as 6-[1-(4-O-methyl-(alpha-d-glucuronyl)-(1, 6)-(beta-d-galactosyloxy]methylpterin by chemical degradation and 1H- and 13C-NMR spectroscopic means. Cyanopterin is constitutively synthesized at a relatively high intracellular concentration that is comparable to that of chlorophyll a in a molar ratio of approximately 1 to 1.6. The in vivo oxidation state of cyanopterin is primarily the fully reduced 5,6,7,8-tetrahydro form. The cellular function is unknown at present. The findings have established a model system, using Synechocystis sp. PCC 6803, for studies of the physiological functions of unconjugated pteridine glycosides found mostly in cyanobacteria.

Current status of vivax malaria among civilians in Korea

A result of national malaria surveillance in Korean civilians was described. Since a case of indigenous vivax malaria was detected in 1993, a total of 2,198 cases was confirmed by blood smear up to 1997. Of them, 1,548 cases were soldiers serving in the demilitarized zone (DMZ), while 650 cases were civilians. Number of civilian cases was 3 in 1994, 19 in 1995, 71 in 1996, and 557 in 1997. Of them, 239 were ex-soldiers who discharged after military service in the prevalent areas such as Paju, Yonchon, Kimpo, Kangwha, Tongduchon in Kyonggi-do and Chorwon in Kangwon-do while 308 patients were civilian residents in the prevalent areas. Seventy-two patients, living nationwide, had a history of visiting the prevalent areas during transmission season. Only 32 civilian patients denied any relation with the prevalent areas. As a whole, a half of the civilian cases was diagnosed when living in non-prevalent areas. Male patients in their twenties was the highest in number. Annual parasite index is steadily elevated in residents living in the prevalent areas. Monthly incidence showed an unimodal distribution, forming a peak in August. Ex-soldiers exhibited a delayed incubation ranging from 153 to 452 days (279 +/- 41 days). The time required for diagnosis was shortened from 23.6 days in 1995 to 13.7 days in 1997. Although the current epidemic of vivax malaria started as a border malaria, it seems highly probable that vivax malaria is established in the local areas and responsible for at least a part of transmission.

NO/cGMP pathway is involved in exocrine secretion from rat pancreatic acinar cells

The enzyme responsible for the synthesis of nitric oxide (NO) from L-arginine in mammalian tissues is known as nitric oxide synthase (NOS) (EC.1.14.13.39). In the present study, the role of NO in the regulation of exocrine secretion was investigated in rat pancreatic acinar cells. Treatment of rat pancreatic acinar cells with cholecystokinin-octapeptide (CCK-OP) resulted in an increase in the arginine conversion to citrulline, the amount of NOx, the release of amylase, and the level of cGMP. Especially, CCK-OP-stimulated increase of arginine to citrulline transformation, the amount of NOx and cGMP level were completely counteracted by the inhibitor of NOS, NG-monomethyl-L-arginine (MMA), by contrast, that of amylase release was partially reduced. Furthermore, MMA-induced decrease of NOS activity and amylase release showed dose-dependent pattern. The data on the time course of CCK-OP-induced citrulline formation and cGMP rise indicate that NOS and guanylate cyclase were activated by treatment of CCK-OP. However, the mechanism of agonist-stimulated guanylate cyclase activation in acinar cells remains unknown. Therefore, activation of NOS is one of the early events in receptor-mediated cascade of reactions in pancreatic acinar cells and NO, not completely, but partially mediate pancreatic enzyme exocrine secretion.

An activator protein-1 (AP-1) response element on pro alpha1(l) collagen gene is necessary for thyroid hormone-induced inhibition of promoter activity in cardiac fibroblasts

Thyroid hormone-induced ventricular hypertrophy is characterized by the absence of fibrosis. Previously, we demonstrated that thyroid hormone inhibits collagen type I gene expression in the myocardium and in cardiac fibroblasts. We also demonstrated that thyroid hormones act as inhibitor of pro alpha1(l) collagen promoter activity. In this study we determined the sequences on pro alpha1(l) collagen gene and transcription factors in cardiac fibroblasts involved in the inhibitory effect of 3,3',5-triiodothyronine (T3). Transient transfection of cells with chloramphenicol acetyl transferase (CAT)-linked deletion mutants of pro alpha1(l) collagen promoter demonstrated that the inhibitory effect of T3 is transmitted via proximal sequences(-225/+115). Gel shift analysis using [32P]-labeled -225/+115 gene fragment and nuclear proteins of cardiac fibroblasts showed T3-induced DNA binding by two proteins. Analysis of non-overlapping restriction sub-fragments by gel shift along with supershift analysis with antibodies to types alpha and beta thyroid hormone receptors identified the lower molecular weight DNA-binding protein as beta receptor and confirmed that the T3-induced protein-DNA binding sites are located at -15/+115. Selective base mutation (C in place of G at +93 and G in place of C at +97) in the activator protein-1 (AP-1) core binding motif(+92/+97) abolished the higher molecular weight T3-induced DNA-protein complex obtained with [32P]-labeled wild type sequences (-225/+115). Additional gel shift analyses using an oligonucleotide containing the AP-1 core binding motif, as an unlabeled competitor and as [32P]-labeled probe, confirmed the T3-induced protein binding to an AP-1 site. Transient transfection with CAT-linked -225/+115 sequences in which the AP-1 site was mutated abolished the T3-induced inhibition of CAT activity. Together, these findings identify sequences necessary for T3-induced inhibition of collagen type I promoter to which thyroid hormone receptor type beta and protein(s) with affinity for AP-1 element bind. They also demonstrate that the AP-1 response element located on these sequences is necessary for T3-induced inhibition of pro alpha1(l) collagen promoter activity. These data identify molecular mechanisms involved in thyroid hormone-induced inhibition of collagen expression in the heart.

p19(Arf) induces p53-dependent apoptosis during abelson virus-mediated pre-B cell transformation

The Ink4a/Arf locus encodes p16(Ink4a) and p19(Arf) and is among the most frequently mutated tumor suppressor loci in human cancer. In mice, many of these effects appear to be mediated by interactions between p19(Arf) and the p53 tumor-suppressor protein. Because Tp53 mutations are a common feature of the multistep pre-B cell transformation process mediated by Abelson murine leukemia virus (Ab-MLV), we examined the possibility that proteins encoded by the Ink4a/Arf locus also play a role in Abelson virus transformation. Analyses of primary transformants revealed that both p16(Ink4a) and p19(Arf) are expressed in many of the cells as they emerge from the apoptotic crisis that characterizes the transformation process. Analyses of primary transformants from Ink4a/Arf null mice revealed that these cells bypassed crisis. Because expression of p19(Arf) but not p16 (Ink4a) induced apoptosis in Ab-MLV-transformed pre-B cells, p19(Arf) appears to be responsible for these events. Consistent with the link between p19(Arf) and p53, Ink4a/Arf expression correlates with or precedes the emergence of cells expressing mutant p53. These data demonstrate that p19(Arf) is an important part of the cellular defense mounted against transforming signals from the Abl oncoprotein and provide direct evidence that the p19(Arf)-p53 regulatory loop plays an important role in lymphoma induction.

The effect of combined epidural and light general anesthesia on stress hormones in open heart surgery patients

This study was designed to evaluate the potential advantages of combined epidural and light general anesthesia over the commonly employed general anesthesia during open heart surgery. Twenty-four patients undergoing mitral valve replacement were thus studied. General anesthesia was maintained with an isoflurane-nitrous oxide-oxygen was mixture and morphine sulfate (0.4 mg/kg i.v. initially) followed by postoperative pain control with morphine in 12 patients (group GA). The remaining 12 patients (group EAA) received continuous epidural bupivacaine (0.125%)-morphine (50 micrograms/ml) supplemented with the same gas mixture as group GA. Epidural infusion was continued until the third postoperative day. Changes in the serum cortisol and beta-endorphin levels together with postoperative pain relief defined as good (scale 0-2), fair (3-4), or poor (5-10) were observed serially. Lower cortisol levels were observed in group EAA than in group GA (P < 0.05) just before skin closure, on the second and the third postoperative day. The beta-endorphin levels were substantially lower in group EAA than in group GA throughout the observation. The pain scores were good in 2 patients (17%), fair in 6 (50%), and poor in 4 (33%) for group GA, and good in 8 (67%), fair in 3 (25%), and poor in 1 (8%) for group EAA. We thus conclude that a combined epidural and light general anesthesia is considered to attenuate the stress response and thereby provides a better quality of postoperative pain control.

Enzymatic methylation of recombinant TIS21 protein-arginine residues

Recombinant TIS21 protein was overexpressed in Escherichia coli harboring the expression vector plasmid pQE-30 carrying the TIS21 cDNA coding sequence containing an extra 120 nucleotides upstream. Employing this protein consisting of 158 amino acid residues of the main chain plus 40 residues of the fusion peptide. It was found that one of the protein methylase I group [S-adenosylmethionine:nuclear protein/histone-arginine N-methyltransferase; BC 2.1.1.23; J. Biol. Chem., 269, 1075 (1994)] methylated this protein. The methylation products were identified as guanidino-N-methylated arginines. Some of the kinetics of the reaction are described.

Farnesylcysteine methyltransferase activity and Ras protein expression in human stomach tumor tissue

The processing pathway of G-proteins and Ras family proteins includes the isoprenylation of the cysteine residue, followed by proteolysis of three terminal residues and alpha-carboxyl methyl esterification of the cysteine residue. Farnesylcysteine methyltransferase (FCMT) activity is responsible for the methylation reaction which play a role in the membrane attachment of a variety of cellular proteins. Four kinds of Ras protein (c-Ha-ras, c-N-Ras, c-Ki-Ras, pan-Ras) expression were detected in adenocarcinoma of human tissue by immunohistochemical method, and hematoxylin and eosin staining. The level of Ras protein in human stomach tumor tissues was much higher than in normal and peritumoral regions of the same biopsy samples. The FCMT activities of each cellular fractions were high in mitochondrial fraction followed by microsomal fraction, whole homogenate and cytosolic fraction. The inhibitory effect on FCMT activity on stomach tumor tissue was determined after treatment with 0.25 microM of S-adenosyl-L-homocysteine. S-adenosyl-L-homocysteine inhibited FCMT activity from 11.2% to 30.5%. These results suggested that FCMT might be involved in Ras proteins activity.

Microsatellite instability in young patients with colorectal cancer

Genetic instability is closely correlated to the pathogenesis of hereditary non-polyposis colon cancer (HNPCC), which is clinically characterized by a family history and early onset. To investigate the role of genetic instability in young patients with colorectal cancer (CRC), 22 CRC patients, who were aged younger than 30 at the time of diagnosis, were studied. Patients with familial adenomatous polyposis were excluded. Among the 22 cases, seven were identified as microsatellite instability positive (MI+), and more than five microsatellite markers among the 15 tested markers showed an additional band pattern in the tumor tissue. None of the remaining 15 cases showed instability in any microsatellite marker. Two of seven MI+ cases were classic HNPCC. While all MI+ cases had one or no metastatic lymph node, 53.3% of MI- cases showed metastasis in two or more regional lymph nodes. Allelic deletion of the 17p12-13 chromosome around the p53 locus occurred in 16.7% of MI+ cases, and 80.0% of MI- cases showed loss of heterozygosity at that locus. hMSH2 Protein expression, assessed by immunohistochemistry, was absent in two cases, both of which were MI+. When we tested two to four sites of MI+ tumors, transforming growth factor beta receptor type II was mutated in a homogeneous pattern in five MI+ cases. In addition, frame-shift mutations of BAX, insulin-like growth factor II receptor, hMSH3 and hMSH6 were found in three cases, five cases, five cases and one case, respectively. In contrast to the consistent mutation of the transforming growth factor-beta receptor type II gene, mutations of other genes varied in different portions of the tumors.

Estrogen enhances proliferative capacity of cardiac fibroblasts by estrogen receptor- and mitogen-activated protein kinase-dependent pathways

The role of female hormones in the prevalence of cardiac diseases are recognized but not fully explored. Proliferation of cardiac fibroblasts, the cellular origin of the extracellular matrix proteins, growth factors and cytokines in the heart, is an important underlying mechanism in the pathophysiological remodeling of the myocardium. In this study, we have investigated the effect of estrogen (17 beta-estradiol) on proliferative capacity of cardiac fibroblasts obtained from adult female rat heart. DNA synthesis, as determined by incorporation of 3H-thymidine into DNA, increased in estrogen-treated cells. In the presence of tamoxifen, an anti-estrogen with high affinity for estrogen receptor. 17 beta-estradiol-induced stimulation of DNA synthesis was abolished. Alpha-estradiol, a stereo-isomer which does not bind the estrogen receptor, did not change DNA synthesis. In the presence of a synthetic inhibitor of MAP kinase pathway. PD98059, estrogen failed to stimulate DNA synthesis. In-gel kinase assays showed rapid and transient increased phosphorylation of MAP kinase substrate, myelin basic protein (MBP), at 42 and 44 kDa by 17 beta-estradiol, which was not observed in the presence of PD98059 and tamoxifen, not induced by alpha-estradiol and persisted in the absence of protein kinase C. In vitro kinase assay confirmed 17 beta-estradiol-induced activation of ERK1 and ERK2, with predominant effect on ERK2 in cardiac fibroblasts. The results of immunofluorescent light microscopy using anti-type alpha and beta estrogen receptor antibodies showed the expression of estrogen receptor types alpha and beta in control untreated cells, and indicated that type beta receptor is the predominant type with both cytoplasmic and nuclear localization. 17 beta-estradiol treatment of cardiac fibroblasts induced the translocation of receptor protein to the nuclei. Together, these data provide evidence that cardiac fibroblasts are cellular targets for direct effects of estrogen, and that this hormone enhances proliferative capacity of cardiac fibroblasts via estrogen receptor- and MAP kinase-dependent mechanisms. These data further suggest that estrogen, by its growth-enhancing effects in cardiac fibroblasts, can regulate the remodeling of the extracellular matrix and alter the microenvironment of cardiac cells, and hence exert an impact on the integrity of myocardial function.

Role of Mxi1 in ageing organ systems and the regulation of normal and neoplastic growth

Mxi1 belongs to the Mad (Mxi1) family of proteins, which function as potent antagonists of Myc oncoproteins. This antagonism relates partly to their ability to compete with Myc for the protein Max and for consensus DNA binding sites and to recruit transcriptional co-repressors. Mad(Mxi1) proteins have been suggested to be essential in cellular growth control and/or in the induction and maintenance of the differentiated state. Consistent with these roles, mxi1 may be the tumour-suppressor gene that resides at region 24-26 of the long arm of chromosome 10. This region is a cancer hotspot, and mutations here may be involved in several cancers, including prostate adenocarcinoma. Here we show that mice lacking Mxi1 exhibit progressive, multisystem abnormalities. These mice also show increased susceptibility to tumorigenesis either following carcinogen treatment or when also deficient in Ink4a. This cancer-prone phenotype may correlate with the enhanced ability of several mxi1-deficient cell types, including prostatic epithelium, to proliferate. Our results show that Mxi1 is involved in the homeostasis of differentiated organ systems, acts as a tumour suppressor in vivo, and engages the Myc network in a functionally relevant manner.