Thermosensing mechanisms and their impairment by high-fat diet in orexin neurons.

In homeotherms, the hypothalamus controls thermoregulatory and adaptive mechanisms in energy balance, sleep-wake and locomotor activity to maintain optimal body temperature. Orexin neurons may be involved in these functions as they promote thermogenesis, food intake and behavioral arousal, and are sensitive to temperature and metabolic status. How thermal and energy balance signals are integrated in these neurons is unknown. Thus, we investigated the cellular mechanisms of thermosensing in orexin neurons and their response to a change in energy status using whole-cell patch clamp on rat brain slices. We found that warming induced an increase in miniature excitatory postsynaptic current (EPSC) frequency, which was blocked by the transient receptor potential vanilloid-1 (TRPV1) receptor antagonist AMG9810 and mimicked by its agonist capsaicin, suggesting that the synaptic effect is mediated by heat-sensitive TRPV1 channels. Furthermore, warming inhibits orexin neurons by activating ATP-sensitive potassium (KATP) channels, an effect regulated by uncoupling protein 2 (UCP2), as the UCP2 inhibitor genipin abolished this response. These properties are unique to orexin neurons in the lateral hypothalamus, as neighboring melanin-concentrating hormone neurons showed no response to warming within the physiological temperature range. Interestingly, in rats fed with western diet for 1 or 11weeks, orexin neurons had impaired synaptic and KATP response to warming. In summary, this study reveals several mechanisms underlying thermosensing in orexin neurons and their attenuation by western diet. Overeating induced by western diet may in part be due to impaired orexin thermosensing, as post-prandial thermogenesis may promote satiety and lethargy by inhibiting orexin neurons.

Streptococcus oricebi sp. nov., isolated from the oral cavity of tufted capuchin.

A Gram-stain-positive, catalase-negative, coccus-shaped organism was isolated from the oral cavity of tufted capuchin (Cebus apella). Comparative 16S rRNA gene sequence analysis suggested classification of the organism within the genus Streptococcus. Strain M8T was related most closely to Streptococcus oralis ATCC 35037T (96.17 % similarity) followed by Streptococcus massiliensis CCUG 49690T (95.90 %) based on the 16S rRNA gene. Strain M8T was related most closely to S. massiliensis CCUG 49690T (86.58 %) based on the RNA polymerase ß subunit-encoding gene (rpoB), and to Streptococcus tigurinus AZ_3aT (81.26 %) followed by S. massiliensis CCUG 49690T (80.45 %) based on the 60 kDa heat-shock protein gene (groEL). The phylogenetic trees of 16S rRNA, rpoB and groEL gene sequences showed that strain M8T was most closely related to S. massiliensis. Based on phenotypic characterization as well as 16S rRNA gene and housekeeping gene (rpoB and groEL) sequence data, a novel taxon, Streptococcus oricebi sp. nov. (type strain M8T = JCM 30719T = DSM 100101T), is proposed.

Presynaptic G Protein-Coupled Receptors Differentially Modulate Spontaneous Glutamate Release in the Supraoptic Nucleus.

Spontaneous glutamate release in the supraoptic nucleus is modulated by a number of inhibitory G protein coupled receptors (GPCR), including GABAB , adenosine A1 and group III metabotropic glutamate receptors (mGluR). It remains unclear whether they have distinct roles or are redundant mechanisms that protect from hyperexcitation. To address this question, we facilitated spontaneous glutamate release using nifedipine or forskolin, which act in a protein kinase A (PKA)-independent and -dependent manner, respectively, and tested the effects of inhibitory GPCR agonists. We found that a GABAB receptor (GABAB R) agonist specifically inhibited forskolin-induced miniature excitatory postsynaptic currents (mEPSC), in contrast to an adenosine A1 receptor (A1R) agonist, which specifically inhibited nifedipine-induced mEPSCs. This suggests that GABAB Rs and A1 Rs modulate independent mechanisms activated by forskolin and nifedipine, respectively. However, the inhibitory effects of GABAB R and A1 R agonists on basal mEPSCs occluded each other, suggesting that these receptors also have an overlapping role. Group III mGluRs appear to have a greater control over glutamate release because agonists to these receptors inhibited both nifedipine- and forskolin-induced mEPSCs. mEPSCs induced by norepinephrine had the same characteristics as those induced by forskolin [i.e. PKA-dependence and sensitivity to GABAB R and group III mGluR agonists, but not an A1 R agonist]. In summary, the present study highlights the differential effects of GABAB R, A1 R and mGluR agonists on glutamate release stimulated by different secretagogues, including the endogenous neuromodulator norepinephrine. These results suggest that the roles of these inhibitory GPCRs are not completely redundant, and also indicate the physiological implications of having different excitatory and inhibitory GPCRs on the same synapse.

Cyclin-dependent kinase 5 is required for normal cerebellar development.

Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase, and its kinase activity is dependent upon its association with either of the activating subunits p35 or p39, which are mainly expressed in neurons. We previously reported that Cdk5 knockout (KO) mice exhibit perinatal lethality, defective neuronal migration, and abnormal positioning of neurons in the facial motor nucleus and inferior olive in the hindbrain and Purkinje cells (PCs) in the cerebellum. In this study, we focused on the analysis of the role of Cdk5 in cerebellar development. For this purpose we generated midbrain-hindbrain-specific Cdk5 conditional knockout (MHB-Cdk5 KO) mice because the cerebellum develops postnatally, whereas Cdk5 KO mice die perinatally. Histological analysis of the MHB-Cdk5 KO mice revealed a significant size reduction of the cerebellum. In addition, profound disturbance of inward migration of granule cells (GC) was observed in the developing cerebellum. A normal dendritic development of the Purkinje cells (PCs) was disturbed in MHB-Cdk5 KO mice. Cultured Cdk5-null PCs showed similar dendritic abnormalities. These results indicate that Cdk5/p35 plays an important role in neuronal migration of PCs and GCs and dendrite formation of PCs in cerebellar development.

Characterization of a new serotype g isolate of Aggregatibacter actinomycetemcomitans.

Aggregatibacter actinomycetemcomitans is usually isolated from the oral cavity where it is associated with active periodontitis. The species can be divided into six serotypes (a-f) according to their surface carbohydrate antigens. However, some clinical isolates cannot be grouped within these six serotypes. Gram-negative, facultative anaerobic, catalase-positive coccobacilli were isolated from a patient with periodontitis and identified by employing genetic, biochemical and serological analyses. Phenotypic data identified the isolate as A. actinomycetemcomitans. Serotype-specific polysaccharide antigen from the isolate was untypeable by immunodiffusion testing in comparison with reference A. actinomycetemcomitans serotype a to f strains. Biofilm formation by the isolate was strong but cytotoxic activity was low. Gas chromatography/mass spectroscopy analysis of partially methylated alditol acetates from surface polysaccharide showed the presence of 2,4-di-O-methyl-rhamnose and 2,3,6-tri-O-methyl-glucose, with a 1 : 1 m ratio. The (1)H- and (13)C-nuclear magnetic resonance spectra of the antigen showed that both constituent glycoses had alpha-anomeric configuration. It is proposed that the untyped strain is a new A. actinomycetemcomitans serotype, designated serotype g.

Genes responsible for dextran-dependent aggregation of Streptococcus sobrinus strain 6715.

INTRODUCTION: Streptococcus sobrinus exhibits more significant dextran-dependent aggregation mediated by glucan-binding proteins than Streptococcus mutans. We have identified four glucan-binding protein C gene (gbpC) homologues designated as gbpC1, gbpC2, dblA and dblB in S. sobrinus in contrast to the single gene gbpC in S. mutans. We attempted to determine which gene is most responsible for the dextran-dependent aggregation of S. sobrinus. METHODS: We introduced mutation with a chemical mutagen, 1-methyl-3-nitro-1-nitrosoguanidine, into S. sobrinus strain 6715 and analysed the four gbpC homologous gene sequences in the parental strain 6715 and an obtained aggregation-negative mutant NUM-Ssg99. We also examined the localization of proteins encoded by these genes in the mutant NUM-Ssg99. RESULTS: The nucleotide sequences of the gbpC1, gbpC2 and dblA genes in NUM-Ssg99 were 100% identical to the homologous genes in parental strain 6715. In contrast, a truncated mutation was detected in the dblB gene and the mutant protein devoid of the LPXTG motif was confirmed by Western blot analysis to be released into the extracellular milieu. CONCLUSION: We conclude that the dblB gene among the four GbpC homologous protein genes is most responsible for aggregation in strain 6715.

A novel selective medium for isolation of Aggregatibacter (Actinobacillus) actinomycetemcomitans.

BACKGROUND AND OBJECTIVE: Conventional selective media have been used for the selection of Aggregatibacter (Actinobacillus) actinomycetemcomitans in clinical samples. The proportion of A. actinomycetemcomitans grown on the selective media in vitro may not reflect the true counts in vivo because of the low selectivity. A novel selective medium, designated AASM, was developed for the isolation of A. actinomycetemcomitans. MATERIAL AND METHODS: AASM was prepared by adding of 200 microg/mL of vancomycin and 10 U/mL of bacitracin to AAGM, which contains dextrose, sodium bicarbonate, trypticase soy, yeast extract and agar. Clinical efficacy was evaluated by the recovery, on AASM, of A. actinomycetemcomitans from subgingival samples of 44 periodontally healthy subjects and 76 patients with chronic periodontitis. RESULTS: All serotypes (a-f) of A. actinomycetemcomitans strains grew well, and the average growth recovery of A. actinomycetemcomitans on AASM medium was 94.4% (80.0-109.7%) of that on AAGM. The exclusive rate of other bacteria was 99.9% in clinical samples cultured on AASM. A. actinomycetemcomitans was not detected in periodontally healthy persons but was detected in 25 (32.9%) patients with chronic periodontitis. The predominant serotype was c, detected in 11 subjects. CONCLUSION: The new selective medium, AASM, was highly selective for A. actinomycetemcomitans, eliminated possible false-positive results and was useful for the isolation of A. actinomycetemcomitans from clinical samples.

Inhibition of acid production in dental plaque bacteria by green tea catechins.

The inhibition of acid production from dental plaque and mutans streptococci by epigallocatechin gallate (EGCg), one of the green tea catechins, was examined. The effect of EGCg solution on dental plaque pH was investigated. Subjects rinsed their mouths with 2 mg/ml EGCg solution and then, after 30-min interval, rinsed their mouths with 10% sucrose. Plaque samples were collected at appropriate times and the pH was measured. The pH values of plaque samples from 15 volunteers were significantly higher after treatment with catechin than after treatment with water. EGCg inhibited pH fall when cariogenic bacteria grown in medium with or without sucrose were incubated with sugar. In medium without sucrose, cultured cells were killed time-dependently by EGCg treatment. However, EGCg did not kill cells cultured in medium containing sucrose. Also, EGCg did not kill oral streptococci adhering to a saliva-coated hydroxyapatite disk. EGCg and epicatechin gallate inhibited lactate dehydrogenase activity much more efficiently than epigallocatechin, epicatechin, catechin or gallocatechin. These results suggest that EGCg is effective in reducing acid production in dental plaque and mutans streptococci.

A novel selective medium for isolation of Streptococcus mutans.

The aim of this study was to improve the selective medium of Streptococcus mutans. A new selective medium, designated MS-MUTV, was prepared by adding 10 mg/l valinomycin to the MS-MUT medium previously described. The average recovery of S. mutans was 72.1%, and the growth of S. sobrinus and S. anginousus group was inhibited on MS-MUTV, but allowed on MS-MUT. One hundred and thirty-nine human saliva samples were examined and counted for S. mutans and non-S. mutans colonies. The recovery of S. mutans on MS-MUTV was similar to that on MS-MUT. Eighty-two and 7.9 percent of the saliva samples obtained S. mutans pure cultures, with no bacterial growth on MS-MUTV, respectively. The remaining 10.1% were contaminated with non-S. mutans, with low-level CFU. MS-MUTV is useful for the isolation of S. mutans alone from clinical samples in routine examinations.

Effect of compensation for scattering angular uncertainty in analytical Compton camera reconstruction.

In Compton cameras, the measured scattering angle is associated with an uncertainty which becomes larger as the incident gamma-ray energy decreases. Since this uncertainty degrades the spatial resolution of reconstructed images, Hirasawa and Tomitani (2003 Phys. Med. Biol. 48 1009-26) previously revised their analytical reconstruction algorithm to compensate for it. As the new algorithm improved the spatial resolution in effect, they expected an enhancement of the statistical noise. In this paper, the effect of this compensation has been analysed in view of spatial resolution (the FWHM of the noise-free reconstructed image for a point source distribution), statistical noise (the relative standard deviation of reconstructed images for an isotropic source distribution) and image quality (the roughness of reconstructed images for a phantom). The results describe not only the effect of the compensation, but also the relation between the statistical noise and three parameters, i.e., the incident gamma-ray energy, the spatial resolution and the measured total event numbers, in reconstruction with compensation. This relation should be taken into account for the design of Compton cameras with good quality images, i.e., useful image, output.

An analytical image reconstruction algorithm to compensate for scattering angle broadening in Compton cameras.

Compton cameras have been developed for use in gamma-ray astronomy and nuclear medicine. Their defining merit is that they do not need collimators; however, on the demerit side, they need inversion procedures for image reconstruction, since a measured datum is proportional to the integration of incident gamma rays along a cone surface with the same Compton scattering angle. First, an iteration method was adopted for this task. Later, analytical methods were found under restricted conditions. Parra (2000 IEEE Trans. Nucl. Sci. 47 1543-50) deduced a purely analytical reconstruction algorithm for a complete set of scattering-projection data that include data at all the scattering angles. Tomitani and Hirasawa (2002 Phys. Med. Biol. 47 2129-45) found that by making a slight modification, Parra's algorithm could be extended to the scattering-projection data in limited scattering angles. However, their algorithm neglected the effects of practical problems that cause the degradation of spatial resolution. Sources of degradation were identified as noise in the energy signal of their front detector and the Doppler effect in the scattering process. In this paper, we first analyse the effects of these sources on the angular resolution of the scattering-projection data and then present a revised reconstruction algorithm in which these two factors are incorporated. Simulation studies on digital phantoms reveal that the algorithm can reconstruct images even when these two factors are included.

A new selective medium for Streptococcus mutans and the distribution of S. mutans and S. sobrinus and their serotypes in dental plaque.

A new selective medium (MS-MUT) was developed for the isolation of Streptococcus mutans from clinical specimens. The average growth recovery of S. mutans on MS-MUT medium was 72.4% of that on MS medium. Growth of Streptococcus sobrinus was significantly inhibited on the medium with an average recovery of 0.034%. In 103 subjects, S. MUTANS was detected at 58.3, 75.0 and 95.7% in the dental plaque of caries-free (CF), caries-inactive (CI) and caries-active (CA) subjects, respectively. S. sobrinus was detected in 8.3, 13.6 and 38.3% of CF, CI and CA subjects, respectively. S. sobrinus alone was detected in only 4.3% of CA subjects. The subjects in whom neither S. mutans nor S. sobrinus were detected were 41.6% in CF and 25.0% in CI. The most predominant serotype was C with a 67% detection rate. S. sobrinus, serotypes D or G were usually found together with S. mutans.

Lipo-prostaglandin E1 is absorbed by vascular smooth muscle cells and may enhance re-endothelialization of vein grafts.

BACKGROUND: Enhancement of re-endothelialization inhibits the progression of intimal hyperplasia. We investigated uptake of Lipoprostaglandin E(1) (LPGE(1)) by endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and effects of the LPGE(1) on re-endothelialization of vein grafts. METHODS: Primary cultured ECs and VSMCs were obtained from mongrel dogs, and incubated in mediums containing 0.5, 5, 50, and 250 ng/ml of DiI-LPGE(1) (DLPGE(1)); its uptake was visualized by the standard rhodamine excitation, and assessed by flow cytometry. In an implantation study, the bilateral femoral veins of 18 animals were implanted into the femoral artery, and the animals were given 0.2 microg/kg LPGE(1) for 2 weeks. Percentages of EC coverage area of the grafts (%EC) were measured by silver nitrate staining at intervals of 3, 7, and 21 days after implantation. RESULTS: VSMCs showed significant uptake in all of the mediums containing DLPGE(1), whereas the ECs revealed no fluorescence. In flow cytometry, histograms of VSMCs showed a specific notch of DLPGE(1), which increased the height according to the grade of the concentrations. The notch did not appear in the histograms of the ECs incubated with any concentration nor in the VSMCs incubated in control medium. These results suggested that LPGE(1) is predominantly absorbed by the VSMCs and exuded PGE(1) then acts on the VSMCs itself and on ECs alike. The %EC at 7 days was 58.4+/-1.9% in the DLPGE(1) group and 31.6+/-6.8% in controls (p<0.05) showing a significant enhancing effect of DLPGE(1) on re-endothelialization of the vein grafts. CONCLUSIONS: In an animal model, daily administration of LPGE(1) resulted in significant enhancement of vein graft re-endothelialization. LPGE(1) was absorbed by the VSMCs, whereas the ECs showed no uptake, therefore the enhancement is probably due to a paracrine effect of VSMCs.

Modulation of synaptic transmission by oxytocin and vasopressin in the supraoptic nucleus.

It is now generally accepted that magnocellular neurons of the supraoptic and paraventricular nuclei release the neuropeptides oxytocin and vasopressin from their dendrites. Peptide release from their axon terminals in the posterior pituitary and dendrites differ in dynamics suggesting that they may be independently regulated. The dendritic release of peptide within the supraoptic nucleus (SON) is an important part of its physiological function since the local peptides can regulate the electrical activity of magnocellular neurons (MCNs) which possess receptors for these peptides. This direct postsynaptic action would affect the output of peptide in the neurohypophysis. Another way that these peptides can regulate MCN activity would be to modulate afferent inputs unto themselves. Although the influence of afferent inputs (inhibitory and excitatory) on SON magnocellular neuron physiology has been extensively described in the last decade, a role for these locally released peptides on synaptic physiology of this nucleus has been difficult to show until recently, partly because of the difficulty of performing stable synaptic recordings from these cells in suitable preparations that permit extensive examination. We recently showed that under appropriate conditions, oxytocin acts as a retrograde transmitter in the SON. Oxytocin, released from the dendrites of MCNs, decreased evoked excitatory synaptic transmission by inhibiting glutamate release from the presynaptic terminals. It modulated voltage-dependent calcium channels, mainly N-type and to a lesser extent P/Q-type channels, located on glutamatergic terminals. Although evidence is less conclusive, it is possible that vasopressin has similar actions to reduce excitatory transmission. This synaptic depressant effect of oxytocin and/or vasopressin, released from dendrites, would ensure that MCNs regulate afferent input unto themselves using their own firing rate as a gauge. Alternatively, it may only be a subset of afferent terminals that are sensitive to these peptides, thereby providing a means for the MCNs to selectively filter their afferent inputs. Indeed its specificity is partly proven by our observation that oxytocin does not affect spontaneous glutamate release, or GABA release from inhibitory terminals (Brussaard et al., 1996). Thus, the dendrites of MCNs of the supraoptic nucleus serve a dual role as both recipients of afferent input and regulators of the magnitude of afferent input, allowing them to directly participate in the shaping of their output. This adds to a rapidly growing body of evidence in support of the concept of a two-way communication between presynaptic terminals and postsynaptic dendrites, and shows the potential of this nucleus as a model to study such form of synaptic transmission.

[Surgery for thymomas and thymic carcinomas; treatment results in terms of WHO histologic typing, Masaoka staging system, and p53 expression].

Forty thymomas and thymic carcinomas were classified in terms of WHO histologic typing, Masaoka staging system, and p53 expression. In WHO histologic typing, type A, AB, B1, B2, B3, and C were 1, 10, 16, 5, 4, and 4 cases, respectively. In Masaoka staging system, I, II, III, and IV were 15, 9, 10, and 6 cases, respectively. Thirteen thymomas exhibited positive p53 expression and 27 did not. Type A and AB thymomas had more favorite prognosis than type B3 and C thymomas, and prognosis of type B1 and B2 was middle. Staging by the Masaoka system also correlated with survival rates. Patients who had p53-negative thymomas survived longer than those who had p53-positive thymomas. A treatment strategy for thymomas and thymic carcinomas should be made on the basis of WHO histologic typing, Masaoka staging system, and p53 expression.

Image reconstruction from limited angle Compton camera data.

The Compton camera is used for imaging the distributions of gamma ray direction in a gamma ray telescope for astrophysics and for imaging radioisotope distributions in nuclear medicine without the need for collimators. The integration of gamma rays on a cone is measured with the camera, so that some sort of inversion method is needed. Parra found an analytical inversion algorithm based on spherical harmonics expansion of projection data. His algorithm is applicable to the full set of projection data. In this paper, six possible reconstruction algorithms that allow image reconstruction from projections with a finite range of scattering angles are investigated. Four algorithms have instability problems and two others are practical. However, the variance of the reconstructed image diverges in these two cases, so that window functions are introduced with which the variance becomes finite at a cost of spatial resolution. These two algorithms are compared in terms of variance. The algorithm based on the inversion of the summed back-projection is superior to the algorithm based on the inversion of the summed projection.

Susceptibility of Streptococcus mutans and Streptococcus sobrinus to cell wall inhibitors and development of a novel selective medium for S. sobrinus.

Representative strains of Streptococcus mutans and Streptococcus sobrinus showed differences in susceptibility to members of the monobactam group of beta-lactam antibiotics: S. sobrinus was less sensitive than S. mutans. The minimum inhibitory concentrations of aztreonam (AZT) and carumonam, both of which belong to this group, were 2,000 microg/ml for S. sobrinus and 125 microg/ml for S. mutans. Further addition of fosfomycin, bacitracin and sodium chloride to Mitis Salivarius agar (MS) supplemented with AZT resulted in growth inhibition of S. mutans and oral streptococci other than S. sobrinus, and was therefore used as a selective medium for S. sobrinus (MS-SOB medium). The average growth recovery of laboratory and clinically isolated strains of S. sobrinus on MS-SOB medium was 74.1% compared to that on MS medium. Seventy-eight percent of clinical samples in which S. sobrinus was detected yielded pure growth of S. sobrinus on MS-SOB medium.

Oxidation-reduction and activation properties of chloroplast fructose 1,6-bisphosphatase with mutated regulatory site.

The concentration of Mg(2+) required for optimal activity of chloroplast fructose 1,6-bisphosphatase (FBPase) decreases when a disulfide, located on a flexible loop containing three conserved cysteines, is reduced by the ferredoxin/thioredoxin system. Mutation of either one of two regulatory cysteines in this loop (Cys155 and Cys174 in spinach FBPase) produces an enzyme with a S(0.5) for Mg(2+) (0.6 mM) identical to that observed for the reduced WT enzyme and significantly lower than the S(0.5) of 12.2 mM of oxidized WT enzyme. E(m) for the regulatory disulfide in WT spinach FBPase is -305 mV at pH 7.0, with an E(m) vs pH dependence of -59 mV/pH unit, from pH 5.5 to 8.5. Aerobic storage of the C174S mutant produces a nonphysiological Cys155/Cys179 disulfide, rendering the enzyme partially dependent on activation by thioredoxin. Circular dichroism spectra and thiol titrations provide supporting evidence for the formation of nonphysiological disulfide bonds. Mutation of Cys179, the third conserved cysteine, produces FBPase that behaves very much like WT enzyme but which is more rapidly activated by thioredoxin f, perhaps because the E(m) of the regulatory disulfide in the mutant has been increased to -290 mV (isopotential with thioredoxin f). Structural changes in the regulatory loop lower S(0.5) for Mg(2+) to 3.2 mM for the oxidized C179S mutant. These results indicate that opening the regulatory disulfide bridge, either through reduction or mutation, produces structural changes that greatly decrease S(0.5) for Mg(2+) and that only two of the conserved cysteines play a physiological role in regulation of FBPase.

Enterovirus RNA replication in cases of dilated cardiomyopathy: light microscopic in situ hybridization and virological analyses of myocardial specimens obtained at partial left ventriculectomy.

OBJECTIVE: Recently, attention has been focused on enteroviral infection of the heart in the genesis of dilated cardiomyopathy (DCM). To determine the location of enteroviral RNA in the myocardium, we performed light microscopic in situ hybridization (ISH) and virological analyses of myocardial specimens obtained at partial left ventriculectomy (PLV). METHODS: Posterolateral walls of the left ventricle from 26 DCM patients were examined. Myocardial specimens were tested for the presence of enteroviral genomes by polymerase chain reaction (PCR). We selected two age-matched groups (10 patients each) in which enteroviruses were either present (EV-plus group) or not (EV-minus group). For both groups, we examined in situ localization of enteroviral RNA in the myocardium by ISH. RESULTS: In PCR studies, both sense and antisense enteroviral RNA were detected in the myocardium of seven patients in the EV-plus group. The presence of this RNA indicates active viral replication in the myocardium. Five of seven patients who exhibited both sense and antisense enteroviral RNA died early after surgery. On ISH, three patients had evidence of active replication of enteroviral genomes. Viral genomes were present in myocardial lesions, especially in endocardial sites. Viral signals were found in degenerating myocardial cells, interstitial inflammatory cells, and endothelial cells of small vessels. These positive signals were not detected in the myocardium of the EV-negative group. CONCLUSIONS: We detected both sense and antisense enteroviral RNA in various myocardial lesions. This suggests that active enteroviral replication plays a role in the development of myocardial lesions in DCM patients. Active viral replication appears to be a prognostic factor for DCM after PLV. Further study of active viral replication in myocardial lesions will provide information useful for evaluating different therapeutic strategies for DCM.

GABA(B) receptors modulate short-term potentiation of spontaneous excitatory postsynaptic currents in the rat supraoptic nucleus in vitro.

High-frequency stimulation of afferents to the supraoptic nucleus (SON) results in a robust increase in the frequency and amplitude of pharmacologically isolated, tetrodotoxin-resistant, miniature excitatory postsynaptic currents (mEPSCs) lasting for 5-20 min. This increase in mEPSC frequency, termed short-term potentiation (STP), is tightly coupled to increases in action potential firing in magnocellular neurons (MCNs) suggesting a functional role for STP. gamma-Aminobutyric acid (GABA), acting selectively on GABA(B) receptors, has been shown to modulate action potential-dependent EPSCs, as well as mEPSCs in this nucleus. In this study, we examined the role of GABA in STP. Using in vitro hypothalamic slices containing the SON and the nystatin perforated-patch recording technique to record from MCNs, we tested the hypothesis that GABA modulates STP. Baclofen, a GABA(B) receptor agonist, caused a reversible decrease in the frequency of mEPSCs as well as a reduction in the magnitude and duration of STP. GABA(B) receptor antagonists blocked the baclofen-induced decrease in mEPSC frequency and reduction in STP. In addition, the antagonists by themselves increased basal mEPSC frequency while prolonging the duration of STP in most cells. By contrast, picrotoxin, a GABA(A) chloride channel blocker, had no effect on STP.These findings indicate that GABA is tonically present in the SON and its action at the GABA(B) receptor may determine the magnitude and duration of STP.