Distribution of vesicular glutamate transporter 1 (VGLUT1) in the mouse esophagus

In rat and mouse esophagus, vesicular glutamate transporter 2 (VGLUT2) has been demonstrated to identify vagal intraganglionic laminar endings (IGLEs); this has recently also been shown for VGLUT1 in rat esophagus. In this study, we have investigated the distribution of VGLUT1 in the mouse esophagus and compared these results with the recently published data from the rat esophagus. Unexpectedly, we have discovered that VGLUT1 mostly fails to identify IGLEs in the mouse esophagus. This is surprising, since the distribution of VGLUT2 shows comparable results in both species. Confocal imaging has revealed substantial colocalization of VGLUT1 immunoreactivity (-ir) with cholinergic and nitrergic/peptidergic markers within the myenteric neuropil and in both cholinergic and nitrergic myenteric neuronal cell bodies. VGLUT1 and cholinergic markers have also been colocalized in fibers of the muscularis mucosae, whereas VGLUT1 and nitrergic markers have never been colocalized in fibers of the muscularis mucosae, although this does occur in fibers of the muscularis running to motor endplates. Thus, VGLUT1 is contained in the nitrergic innervation of mouse esophageal motor endplates, another difference from the rat esophagus. VGLUT1-ir is therefore present in extrinsic and intrinsic innervation of the mouse esophagus, but the significant differences from the rat indicate species variations concerning the distribution of VGLUTs in the peripheral nervous system.

Benefits of an external focus of attention: Common coding or conscious processing?

We conducted two experiments to assess the effect attentional focus has on learning a complex motor skill and subsequent performance under secondary task loading. Participants in Experiment 1 learnt a golf putting task (300 practice trials) with a single instruction to either focus on their hands (internal focus) or the movement of the putter (external focus). No group differences were evident during learning or retention. Differences between the groups were only apparent under secondary task load; the external group's performance remained robust, while the internal group suffered a drop in performance. Verbal protocols demonstrated that the internal group accumulated significantly more internal knowledge and more task-relevant knowledge in general than the external group. Experiment 2 was designed to establish whether greater internal focus knowledge or greater explicit rule build up in general was responsible for performance breakdown. Two groups were presented with a set of six internal or external rules. Again, no performance differences were found during learning or retention. During the secondary task, both groups experienced performance deterioration. It was concluded that accumulation of explicit rules to guide performance was responsible for the internal group's breakdown in performance under secondary task loading and may be responsible for some of the performance differences reported previously.

Vesicular glutamate transporter 1 immunoreactivity in extrinsic and intrinsic innervation of the rat esophagus

Encouraged by the recent finding of vesicular glutamate transporter 2 (VGLUT2) immunoreactivity (-ir) in intraganglionic laminar endings (IGLEs) of the rat esophagus, we investigated also the distribution and co-localization patterns of VGLUT1. Confocal imaging revealed substantial co-localization of VGLUT1-ir with selective markers of IGLEs, i.e., calretinin and VGLUT2, indicating that IGLEs contain both VGLUT1 and VGLUT2 within their synaptic vesicles. Besides IGLEs, we found VGLUT1-ir in both cholinergic and nitrergic myenteric neuronal cell bodies, in fibers of the muscularis mucosae, and in esophageal motor endplates. Skeletal neuromuscular junctions, in contrast, showed no VGLUT1-ir. We also tested for probable co-localization of VGLUT1-ir with markers of extrinsic and intrinsic esophageal innervation and glia. Within the myenteric neuropil we found, besides co-localization of VGLUT1 and substance P, no further co-localization of VGLUT1-ir with any of these markers. In the muscularis mucosae some VGLUT1-ir fibers were shown to contain neuronal nitric oxide synthase (nNOS)-ir. VGLUT1-ir in esophageal motor endplates was partly co-localized with vesicular acetylcholine transporter (VAChT)/choline acetyltransferase (ChAT)-ir, but VGLUT1-ir was also demonstrated in separately terminating fibers at motor endplates co-localized neither with ChAT/VAChT-ir nor with nNOS-ir, suggesting a hitherto unknown glutamatergic enteric co-innervation. Thus, VGLUT1-ir was found in extrinsic as well as intrinsic innervation of the rat esophagus.

Number and distribution of intraganglionic laminar endings in the mouse esophagus as demonstrated with two different immunohistochemical markers

Intraganglionic laminar endings (IGLEs) represent the only vagal mechanosensory terminals in the tunica muscularis of the esophagus. Two specific markers for IGLEs were recently described in mouse: the purinergic P2 x 2 receptor and the vesicular glutamate transporter 2 (VGLUT2). This study aimed at comparing both markers with respect to their suitability for quantitative analysis. We counted IGLEs immunostained for VGLUT2 and P2 x 2, respectively, and mapped their distribution in esophageal wholemounts of C57Bl/6 mice. Numbers and distribution of IGLEs were compared with those of myenteric ganglia as demonstrated by cuprolinic blue histochemistry. Whereas the distribution of VGLUT2-immunopositive IGLEs closely matched that of myenteric ganglia, P2 x 2-immunopositive IGLEs were rarely found in upper and middle esophagus but increasingly in its lower parts. P2 x 2 stained only half the number of IGLEs found with VGLUT2 immunostaining. We also investigated the correlation between anterograde tracing and immunohistochemistry for identifying IGLEs. Confocal microscopy revealed colocalization of all three markers in approximately 50% of IGLEs. The remaining IGLEs showed only tracer and VGLUT2 labeling but no P2 x 2 immunoreactivity. Thus, VGLUT2 and P2 x 2 represent two specific markers for qualitative demonstration of esophageal IGLEs. However, VGLUT2 may be superior to P2 x 2 as a quantitative marker for IGLEs in the esophagus of C57Bl/6 mice.

Intraganglionic laminar endings and their relationships with neuronal and glial structures of myenteric ganglia in the esophagus of rat and mouse

Intraganglionic laminar endings (IGLEs) represent the only vagal mechanosensory terminals in the tunica muscularis of the esophagus and may be involved in local reflex control. We recently detected extensive though not complete colocalization of the vesicular glutamate transporter 2 (VGLUT2) with markers for IGLEs. To elucidate this colocalization mismatch, this study aimed at identifying markers for nitrergic, cholinergic, peptidergic, and adrenergic neurons and glial cells, which may colocalize with VGLUT2 outside of IGLEs. Confocal imaging revealed, besides substantial colocalization of VGLUT2 and substance P (SP), no other significant colocalizations of VGLUT2 and immunoreactivity for any of these markers within the same varicosities. However, we found close contacts of VGLUT2-positive structures to vesicular acetylcholine transporter, choline acetyltransferase, neuronal nitric oxide synthase, galanin, neuropeptide Y, and vasoactive intestinal peptide immunoreactive cell bodies and varicosities, as well as to glial cells. Neuronal perikarya were never positive for VGLUT2. Thus, VGLUT2 was almost exclusively found in IGLEs and may serve as a specific marker for them. In addition, many IGLEs also contained SP. The close contacts established by IGLEs to myenteric cell bodies, dendrites, and varicose fibers suggest that IGLEs modulate various types of enteric neurons and vice versa.

Binge-eating episodes are not characteristic of carriers of melanocortin-4 receptor gene mutations

Recently, Branson and coworkers reported a strong association between binge-eating disorder (BED) and variants in the melanocortin-4 receptor gene (MC4R). In the current study, we compared the eating behavior of 43 obese probands with functionally relevant MC4R mutations and of 35 polymorphism carriers (V103I or I251L) with wild-type carriers. The module for eating disorders of the Composite International Diagnostic Interview was used to identify binge-eating behavior. The Three-Factor Eating Questionnaire and the Leeds Food Frequency Questionnaire were used to assess restrained eating, disinhibition, hunger and percent total energy intake as fat. No significant differences between carriers of MC4R variants and wild-type carriers were detected. In particular, we found no evidence for an increased rate of binge-eating behavior in obese carriers of MC4R variants. Our findings do not support the strong association between BED and MC4R carrier status.

Vesicular glutamate transporter 2 immunoreactivity in putative vagal mechanosensor terminals of mouse and rat esophagus: indication of a local effector function?

Intraganglionic laminar endings (IGLEs) represent the major vagal afferent structures throughout the gastrointestinal tract. Previous ultrastructural investigations have revealed synaptic contacts of IGLEs on myenteric neurons. Thus, in addtion to functioning probably as mechanosensors, IGLEs may also synaptically influence myenteric neurons. In search of clues for potential transmitters in IGLEs, we investigated, by combined neuronal tracing and immunocytochemistry in the esophagus, the correlation between IGLEs and vesicular glutamate transporter 2 (VGLUT2), which is considered a reliable marker for glutamatergic neurons. In rat esophagus, IGLEs were immunostained with calretinin. In the mouse, anterograde wheat germ agglutinin/horseradish peroxidase (WGA-HRP) tracing from nodose ganglion was used in order to label esophageal IGLEs. Confocal laser scanning microscopy demonstrated that VGLUT2 immunoreactivity was highly colocalized with synaptophysin and that both calretinin and tyramide amplified WGA-HRP in rat and mouse esophagus, respectively. No colocalization was found with calcitonin gene-related peptide, a marker for spinal primary afferents. Thus, VGLUT2 is found in vagal afferent endings in the esophagus, suggesting that glutamate is contained in, and probably released from, synaptic vesicles previously described in IGLEs. Functional evidence pending, this finding is in favor of a local effector function of IGLEs onto myenteric neurons.

Determination of fifteen nucleotides in cultured human mononuclear blood and umbilical vein endothelial cells by solvent generated ion-pair chromatography

The paper describes the development of a method for the determination of 15 nucleotides in cultured mononuclear blood and umbilical vein endothelial cell lysates by solvent generated ion-pair chromatography. The phase system is generated via a mobile phase of 100 mM phosphoric acid adjusted to pH 6.2 with triethylamine. Nucleotides are eluted by applying a linear magnesium ion gradient. The method is robust, highly reproducible and easily adaptable to other cell lysates and allows the separation and quantitation of the nucleotides with detection limits in the range from 17 (ADP) to 126 (CDP) pmol in 20-microl aliquots.

Surgery of a splenic artery aneurysm during pregnancy

We report a case of ligation of the splenic artery with splenectomy during pregnancy due to a splenic artery aneurysm. The risk of aneurysmal rupture is increased in multipara and during pregnancy. As a result of high maternal and fetal morbidity and mortality elective surgery should be performed.

Endothelial cell compatibility of azithromycin and erythromycin

Phlebitis is a severe local adverse event related to the use of parenteral macrolides. In order to evaluate the effect of azithromycin and erythromycin on human venous endothelial cells, we set up an in vitro model. The intracellular levels of purine nucleotides, as adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP) and guanosine 5'-triphosphate (GTP), were measured by means of high-performance liquid chromatography. Incubation of cells with 2 mg/mL azithromycin and erythromycin resulted in a rapid decline of intracellular ATP from 12.5 +/- 0.9 nmol/million cells to 4.1 +/- 0.3 and 2.6 +/- 0.4 nmol/million cells, respectively, after 60 min. In addition, ADP was extensively depleted from 2.1 +/- 0.17 nmol/million cells to 0.8 +/- 0.09 and 0.8 +/- 0.13 nmol/million cells after 60 min. After exposure of 0.5 mg/mL azithromycin and erythromycin, no significant decline of intracellular high-energy phosphate levels occurred after 20 and 60 min. Based on these results, solutions of azithromycin and erythromycin may not be well tolerated and may cause local adverse reactions even if diluted according to the manufacturer's recommendation.

CD28 signaling via VAV/SLP-76 adaptors: regulation of cytokine transcription independent of TCR ligation

Since CD28 provides cosignals in T cell responses, a key question is whether the coreceptor operates exclusively via TCRzeta/CD3 or also operates as an independent signaling unit. In this study, we show that CD28 can cooperate with VAV/SLP-76 adaptors to upregulate interleukin 2/4 transcription independently of TCR ligation. CD28 signaling is dependent on VAV/SLP-76 complex formation and induces membrane localization of these complexes. CD28-VAV/SLP-76 also functions in nonlymphoid cells to promote nuclear entry of NFAT, indicating that these adaptors are the only lymphoid components needed for this pathway. Further downstream, CD28-VAV/SLP-76 synergizes with Rac1 and causes F-actin remodelling proximal to receptor. Autonomous CD28 signaling may account for the distinct nature of the second signal and in trans amplification of T cell responses.

Positive regulation of T cell activation and integrin adhesion by the adapter Fyb/Slap

The molecular adapter Fyb/Slap regulates signaling downstream of the T cell receptor (TCR), but whether it plays a positive or negative role is controversial. We demonstrate that Fyb/Slap-deficient T cells exhibit defective proliferation and cytokine production in response to TCR stimulation. Fyb/Slap is also required in vivo for T cell-dependent immune responses. Functionally, Fyb/Slap has no apparent role in the activation of known TCR signaling pathways, F-actin polymerization, or TCR clustering. Rather, Fyb/Slap regulates TCR-induced integrin clustering and adhesion. Thus, Fyb/Slap is the first molecular adapter to be identified that couples TCR stimulation to the avidity modulation of integrins governing T cell adhesion.

In vitro effects of mycophenolic acid on the nucleotide pool and on the expression of adhesion molecules of human umbilical vein endothelial cells

The immunosuppressive drug mycophenolate mofetil (MMF) and its active metabolite mycophenolic acid (MPA) selectively inhibit inosine 5'-monophosphate dehydrogenase (IMPDH), and therefore interfere with cellular guanine nucleotide biosynthesis. IMPDH is additionally involved in the synthesis of membrane glycoproteins, some of which are adhesion receptors known to play an active part in the regulation of cell-cell contacts, which are crucial in the process of recruitment and transendothelial infiltration of activated leucocytes in the transplanted organ. As a consequence, MPA leads to a reduction of cellular infiltrates in the course of transplant rejection. In the present study, the effects of MPA on human umbilical vein endothelial cells (HUVEC) are investigated at both molecular and cellular levels. In our experiments, HUVECs are treated with tumor necrosis factor-alpha (TNF-alpha; 10 ng/ml) in order to mimic activation occurring at a rejection crisis. The dose-dependent influence of concomitant incubation with MPA (5-20 micromol/l; 48 h, 37 degrees C, 5% CO2) on their intracellular nucleotide profile is observed by determining the concentrations of purine and pyrimidine nucleotides, using a HPLC method based on solvent generated ion-exchange. The possibility of synergistic effects is investigated by incubating endothelial cells with mixtures of three different immunosuppressants (mycophenolic acid; cyclosporin A, 100 ng/ml; prednisolone, 1 micromol/l)--a combination commonly used after transplantation--varying the amount of MPA (5-20 micromol/l). Stimulation with TNFalpha does not significantly modulate the intracellular levels of nucleotides quantitated. In the presence of MPA concentrations of at least 5 micromol/l, GTP levels (68+/-12%) are significantly decreased compared to controls (100%). At a concentration of 20 micromol/l MPA, the GTP amount is reduced to 58+/-7%. In contrast to these observations, the levels of UDP and UTP are increasing significantly under coincubation with MPA concentrations greater than 5 micromol/l. At 20 micromol/l MPA, UDP and UTP are increased to 147+/-19% and 114+/-11%, respectively. All other nucleotides (CTP, ADP, ATP) reveal no significant alterations in their intracellular concentrations under the conditions applied. Incubation of TNFalpha-treated HUVEC monolayers, with a mixture of three immunosuppressive drugs varying the amount of MPA, show no significant differences compared with the data observed after incubation with MPA alone. In addition, the influence of MPA (10 micromol/l) on a cellular level is observed by measuring the cell surface expression of adhesion molecules on cytokine-stimulated HUVECs, using TNFalpha (10 ng/ml), interferon-gamma (100 ng/ml), interleukin-1beta (10 ng/ml) and interleukin-8 (20 ng/ml). Expression of the intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), endothelial leucocyte adhesion molecule-1 (ELAM-1) and platelet endothelial cell adhesion molecule-1 (PECAM-1) was assessed by flow cytometry. Activation of endothelial cell monolayers with TNFalpha significantly increases the mean fluorescence intensity of VCAM-1 (361+/-14%) and ICAM-1 (429+/-47%) surface expression, compared to controls, and additionally induces E-selectin expression (2919+/-134%). The same tendencies, but in a lesser degree, are observed under stimulation of cells with either IFNgamma or IL-1beta. Incubation with a combination of TNFalpha and MPA leads to a significant reduction in VCAM-1 (329+/-13%) and E-selectin (2613+/-167%) expression, compared to the values obtained for HUVEC incubated with the cytokine alone. Treatment of the cells with IL-1beta/MPA also reduces the expression of VCAM-1 to a level significantly lower than the level observed after stimulation with IL-1beta. Incubation with MPA alone reveals no significant modulation in the expression of all surface molecules tested compared to the values of unstimulated HUVECs. The experiments show that the immunosuppressive action of MPA not only inhibits lymphocyte proliferation but also decreases the expression of adhesion molecules on endothelial cells, which are the first target of the cellular rejection process.

Determination of the effects of mycophenolic acid on the nucleotide pool of human peripheral blood mononuclear cells in vitro by high-performance liquid chromatography

Immunosuppressive drugs are needed to prevent the rejection of transplanted organs by the immune system. Immunosuppressive antimetabolites act by interrupting cell metabolism. Their mechanism of action can be studied in vitro by measuring the inhibition of biochemical activities which is reflected by changes in the nucleotide content. In our experiments, human peripheral blood mononuclear cells (PBMC) isolated from healthy volunteers were used. After PBMC stimulation with phytohaemagglutinin (PHA) to mimic activation occurring at a rejection crisis, cells were exposed to varying concentrations of different immunosuppressants (i.e., mycophenolic acid, cyclosporin A and prednisolone) for 68 h at 37 degrees C. Changes in nucleotide content were observed by determining the concentrations of 15 nucleotides using a newly developed HPLC method. The results obtained for mycophenolic acid (MPA; final concentrations in a range between 0.1 and 5 micromol/l), cyclosporin A (CsA; final concentrations between 100 ng/ml and 1 microg/ml) and prednisolone (final concentrations between 0.5 and 10 micromol/l) are given as percentage changes in nucleotide content versus controls and are expressed as mean +/- confidence interval. The possibility of synergistic effects was investigated by incubating the cells with mixtures of all three immunosuppressive drugs varying the amount of mycophenolic acid. In addition, we have shown the effects of MPA/guanosine co-incubation on the intracellular nucleotide levels. Stimulation of peripheral blood mononuclear cells with phytohaemagglutinin led to a significant increase of pyrimidine and purine nucleotides versus control values (100%). Pyrimidine (CTP, UDP, UTP) and purine nucleotides (GDP, GTP, ADP, ATP) were elevated up to 153+/-14% and 142+/-17%, respectively. Under co-incubation of cells with MPA, the GTP level decreased in a dose-related manner to 56+/-3% of control at a MPA final concentration of 5 micromol/l. Concomitantly, an increase of UTP values to 203+/-18% versus control was observed under co-incubation with 1 micromol/l MPA. Co-incubation of mononuclear cells with guanosine (50 micromol/l) compensated for the effects of MPA on intracellular GTP levels. Combination of MPA, CsA and prednisolone did not alter intracellular nucleotide profiles of PBMC compared to those under MPA incubation alone. The depletion of the guanine nucleotide pool and concomitant increase of uridine nucleotides under the influence of the immunosuppressive drug mycophenolic acid is caused by its inhibitory effects on the key enzyme of de novo purine biosynthesis, inosine 5'-monophosphate dehydrogenase (IMPDH).